# Garage Workshop build - advice needed please



## Goesbysteve (5 Oct 2022)

I am currently planning the fit out of an existing double garage as a workshop and I really need some advice. I’d like any thoughts on my situation, plans or anything I’m missing please. I’m sorry for the long post but I hope it gets all the details in. I appreciate anyone who reads it. My post is in two sections. Dealing with flood risk and fit out of garage.

To give you an idea of the location -











The garage is a post 2000 (maybe 2007) dated 3m x 6m single skin concrete block wall with wooden pitched roof and swinging wooden doors. There is a flat concrete slab floor in good condition. I’m unsure if any damp proofing on the slab as it predates our ownership. Should I try to find the builder and get details? Given I live in rural north mid-Wales right next to a river and a stream and the rear of the garage built into earth covering approx 30cm of wall above the slab I am thinking additional protection. Although neighbours have said the house hadn’t flooded in 25+ years of their living here I was told by a previous resident that the property did flood around 1938. From what I’ve been told as we are in the hills water tends to come and go quickly so I am not thinking I need to deal with long term flood. As part of a flood risk mitigation project I probably will look at slot-in flood walls on our front door and the garage. These typically come up to 45cm. However I would want to double up on interior protection for the garage. Maybe a DPM sheet across floor and 30cm up the wall? I wonder if that would deal with any ingress through walls should water get above the concrete slab level. How resistant are concrete blocks and mortar to ingress? Is there any benefit to using a paint on sealer either inside or outside to tank the lower level? Would this actually help? The garage has a black paint on the walls. I’m unsure if this is just regular paint or something like Black Jack bitumen. Anyone know how to tell the difference? It covers the entire wall height.

I realise there will be some comments to not be so mad to build workshop here but it’s an existing building and I don’t have the money to build a workshop from scratch. But help really appreciated on basis of protection. A flood is actually an unlikely occurrence but I’d like to understand my options.

As to the fit out. The roof is built of C24 2x3 rafters and ceiling beams/ties. Doubled up in some locations. Both ends and centre I think. Currently I use the roof space to store suitcases, TV shipping boxes etc. nothing of considerable weight. I would like to insulate between beams and lay sheet material to allow better storage up there. Would -50mm PIR be suitable? I’m limited on thickness given the 3x2s used. I would probably put plasterboard on the underside. Should 2x3s be able to take that weight or am I asking too much of them? What options might I have of reinforcing? Can I build out the walls first then get to the ceiling at a later date?










On the walls I’d like to insulate. I realise there are many options but I was leaning towards a stud wall of 2x3 with -50mm rigid PIR insulation and OSB faced. I will want to add robust shelving to the walls. There is one double glazed window in the back wall. I’ve seen battening direct to walls with -25mm blue treated timber and a DPM roll between wall and batten. I wasn’t sure if that is ok too in my situation. The latter would reduce the space taken up a little. If I go the stud wall route how much of an air-gap should I leave? I’ve seen various ways probably on buildings with far more space than I have here so I don’t want to just go with what had worked for someone else’s building. What are my other options here? If I use PIR that has a film layer both sides do I need an additional breathable layer? I know OSB along with other typical wall panelling is not that water resistant, especially if actually in water. I know there are metal and plastic options but I think they are going to be out of my budget. OSB would he replaceable should the worst happen. How does PIR hold up to water?

On the floor I wasn’t going to insulate specifically. I would add a DPM if necessary and lay interlocking PVC garage tiles. My thoughts here is if I do get any water I want anything on the floor to be essentially waterproof and removable.






The electrics are already in the garage and I have plenty of sockets. RCD and wiring is at the top of the walls and sockets at 1.5m above the floor. I guess I need to release everything from the wall and the replace them back on the surface.






That leaves the wooden doors. They are well fitting and heavy. There is a 25mm rise on the floor level that the doors close against. I’m not sure what to do here but given effort I’d go to to insulate they will be the weak link. Would PIR be an option here again?






I was thinking about having an oil filled radiator set low to come on at 5C. I can then set it higher to get the workshop warm enough to work in. 16C would do me plenty. I don’t mind wearing a fleece lined work shirt! I know little on capacity of rad to deal with freezing temps outside in a garage my size. Would appreciate any advice on this too,

Finally at the end! Thanks for reading. Sorry if I have missed anything or not explained well enough. please do ask for clarification. Again I really do appreciate your advice.


Diolch yn fawr!

Warm regards,

Steve


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## Goesbysteve (5 Oct 2022)

I have just realised these are “breeze blocks” with no render on the outside. I think they have been painted with something to try to waterproof it. I’ll need to dig around the rear where the ground build up against the wall to see what below. Hmmmm I can see more cost coming in. At least external wouldn’t delay interior build. But i feel tanking or DPM roll on the floor is needed.

may have to find money from switching from PIR to rockwool.


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## Jameshow (6 Oct 2022)

I think your roof structure is fine for boarding out and plasterboarding. 

If your worried about a flood which you say the risk is very low then how about doing the bottom 1/2 ft in cement board which is impervious to water? 

Putting a coating of liquid DPM wouldn't go amiss. 

Digging out behind the garage and back filling with gravel might be an idea if you feel the back wall to be damp?

If your putting a flood defense system in then I don't think you need to worry too much apart from the worry that your away when it does flood.


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## MikeJhn (6 Oct 2022)

If flooding is a risk, ensure all the electrics are at a high level.

Personally I would give up woodworking and spend my time fly fishing in that extremely good looking stream.


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## Goesbysteve (6 Oct 2022)

MikeJhn said:


> If flooding is a risk, ensure all the electrics are at a high level.
> 
> Personally I would give up woodworking and spend my time fly fishing in that extremely good looking stream.


It is a lovely looking stream but full of lead due to historic mining. However I think fishing is more about the experience than actually catching anything!


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## Goesbysteve (6 Oct 2022)

Jameshow said:


> I think your roof structure is fine for boarding out and plasterboarding.


thanks, I’d seen so many YouTube videos of 4x2 and 6x2 used for joists that I was worrying that my thin 3x2 wouldn’t take much weight. I’m not about to go dancing a jig up there but I would want to crawl around to get insulation between the joists. Would you feel ok doing that yourself If that were your roof?


Jameshow said:


> If your worried about a flood which you say the risk is very low then how about doing the bottom 1/2 ft in cement board which is impervious to water?



Interesting idea, thanks. I’d not heard if that. Makes complete sense. I will research that.


Jameshow said:


> Putting a coating of liquid DPM wouldn't go amiss.



I guess a DPM is to stop water travelling into the garage through the slab rather than flood water?


Jameshow said:


> Digging out behind the garage and back filling with gravel might be an idea if you feel the back wall to be damp?



that’s an option. However I have my oil heating tank behind the garage. Even though it sits on a substantial concrete slab itself I’d be concerned about back filling with anything that holds back the ground up hill from subsiding down. I think there are two things I need to worry about here. Non-flood Welsh weather where there is a lot of water held in the ground and actual flood. I can add something to assist in draining for the regular cinditions but when it floods that water could have no where to drain. Hence thinking a barrier to hold it back from the wall long enough fir the flood to drain. It comes and goes quite quickly here. Like hours, not days, touch wood. That said assisting drainage might not be a bad idea the other side assuming I can deal with the support issue.



Jameshow said:


> If your putting a flood defense system in then I don't think you need to worry too much apart from the worry that your away when it does flood.


yes indeed. we get a bit of warning and I work from home. We alsoI have lovely neighbours round here and if away for a holiday I’d be putting the system up and locking it as additional theft protection.


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## Goesbysteve (6 Oct 2022)

Is moisture resistant plasterboard worth it in my situation?


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## johna.clements (6 Oct 2022)

Goesbysteve said:


> that’s an option. However I have my oil heating tank behind the garage. Even though it sits on a substantial concrete slab itself I’d be concerned about back filling with anything that holds back the ground up hill from subsiding down. I think there are two things I need to worry about here. Non-flood Welsh weather where there is a lot of water held in the ground and actual flood. I can add something to assist in draining for the regular cinditions but when it floods that water could have no where to drain. Hence thinking a barrier to hold it back from the wall long enough fir the flood to drain. It comes and goes quite quickly here. Like hours, not days, touch wood. That said assisting drainage might not be a bad idea the other side assuming I can deal with the support issue.


The high ground built up against the garage and the flooding from the river are different issues.

The high ground keeps moisture against the wall which will then penetrate making the inside damp. If you do not want to have a wide shallow trench you could dig a narrow one and retain the 300mm high side with blocks to match the garage or paving slabs laid vertacally or a slight angle. Just leave a gap wide enough to clean out leaves etc A photo would help. 

The ground being higher at this point is unlikely to make the flooding from the river worse. It may in fact help in a small way, a bit like putting sand bags against the garage.

Unless there is a bridge just downstream that could be blocked by trees in a flood I would doubt that the water would stay there for long. If the high ground has been underwater it will have soaked up some water but most likely not more than weeks of heavy rain.


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## niall Y (6 Oct 2022)

A beautiful location, but with the river there a hostage to future flooding. As someone whose workshop has flooded twice in the last 14 years, it can be a bit of a PITA. Anything that you can reasonably do to mitigate the effects, is well worth doing at this early stage.
I can't imagine that the guys who put up your garage did not tank the back, where it touches the bank, otherwise you would already have a problem inside the garage. I would assume that this amounts to more than a couple of coats of 'Black Jack', though you never can tell

When we moved into our property, I converted our lean -to garage into an additional bedroom. This was a concrete block construction. Building regs required that I coat the walls with bitumen paint, before, battening it out and fitting 'Cellotex' panels. The choice was then, either to cover this with foiled plasterboard, or to use a thin polythene sheet with ordinary plasterboard on top. Admittedly, yours is a workshop, but something along these lines, is what is required, Though if it's going to get wet some time during its life, some form of cement board might be better.

With reference to the existing doors, I have improved the insulation of this type of door, by first covering with a breathable membrane, infilling with 'Cellotex', and finally covering with board or T&G


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## johna.clements (6 Oct 2022)

niall Y said:


> A beautiful location, but with the river there a hostage to future flooding. As someone whose workshop has flooded twice in the last 14 years, it can be a bit of a PITA. Anything that you can reasonably do to mitigate the effects, is well worth doing at this early stage.
> I can't imagine that the guys who put up your garage did not tank the back, where it touches the bank, otherwise you would already have a problem inside the garage. I would assume that this amounts to more than a couple of coats of 'Black Jack', though you never can tell


I would assume that the oil tank was built after the garage. The garage looks well constructed. I would assume that the people who put in the base did not care about the levels of the ground "its just a garage".


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## Goesbysteve (6 Oct 2022)

niall Y said:


> A beautiful location, but with the river there a hostage to future flooding. As someone whose workshop has flooded twice in the last 14 years, it can be a bit of a PITA. Anything that you can reasonably do to mitigate the effects, is well worth doing at this early stage.
> I can't imagine that the guys who put up your garage did not tank the back, where it touches the bank, otherwise you would already have a problem inside the garage. I would assume that this amounts to more than a couple of coats of 'Black Jack', though you never can tell


Thanks for the reply. Yes it is, we are very lucky. But it comes with risks as you say.

oh I can imagine all sorts not done right here. they painted the breeze block with “something” rather than render or glad it. I’m still to work out what the black paint from top to bottom of walls actually is. I’m going to have an exploratory dig around the rear at the weekend. Assuming rain holds off.


niall Y said:


> When we moved into our property, I converted our lean -to garage into an additional bedroom. This was a concrete block construction. Building regs required that I coat the walls with bitumen paint, before, battening it out and fitting 'Cellotex' panels. The choice was then, either to cover this with foiled plasterboard, or to use a thin polythene sheet with ordinary plasterboard on top. Admittedly, yours is a workshop, but something along these lines, is what is required, Though if it's going to get wet some time during its life, some form of cement board might be better.



If I understood you correctly the walls were painted with black jack on the inside? What was on the outside out of interest?

I definitely want OSB 3 as the inside surface and my budget is only going to reach to rock wool I think. I believe a 50mm airbag between inside of wall and insulation is required if regs applied here. I may only get 25mm and 50mm insulation with 12.5mm OSB over it So I don’t lose too much space. I’m on my getting the rear half as a workshop and the rest is storage and supplies. E.g. two extra fridge freezers.

was the polythene sheet a vapour barrier? I’m not sure I’d be producing enough moisture that could escape through rock wool and get drawn out by airgap. However on the walls I’m not sure how a threw flow is achieved as it would be in my loft. 


niall Y said:


> With reference to the existing doors, I have improved the insulation of this type of door, by first covering with a breathable membrane, infilling with 'Cellotex', and finally covering with board or T&G



I may be able to go with PIR infill on the doors as anything loose is impractical there. thin painted OSB 3 or exterior ply over it? The doors when open may get some rain. Hence wanting more protection there than the interior walls.


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## Goesbysteve (6 Oct 2022)

johna.clements said:


> I would assume that the oil tank was built after the garage. The garage looks well constructed. I would assume that the people who put in the base did not care about the levels of the ground "its just a garage".


I think at the same time. The owner then was renovating the entire property.


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## Goesbysteve (6 Oct 2022)

johna.clements said:


> The high ground built up against the garage and the flooding from the river are different issues.



completely agree


johna.clements said:


> The high ground keeps moisture against the wall which will then penetrate making the inside damp. If you do not want to have a wide shallow trench you could dig a narrow one and retain the 300mm high side with blocks to match the garage or paving slabs laid vertacally or a slight angle. Just leave a gap wide enough to clean out leaves etc A photo would help.



I was thinking the same but living in a conservation area may cause issues even when it’s unseen by anyone and the garage is hardly in keeping.

Yes it’s hard to visualise, I will sort some photos


johna.clements said:


> The ground being higher at this point is unlikely to make the flooding from the river worse. It may in fact help in a small way, a bit like putting sand bags against the garage.
> 
> Unless there is a bridge just downstream that could be blocked by trees in a flood I would doubt that the water would stay there for long. If the high ground has been underwater it will have soaked up some water but most likely not more than weeks of heavy rain.



There is a fairly decent stone bridge 50m away downstream. It’s field upstream and not woodland though it only takes one tree. I think the flood defences on the door plus suitable waterproofing on outside of walls would be the best I can do. Is Black Jack high up the wall enough for that?


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## Jones (6 Oct 2022)

As there's no cavity in the wall you will need to do something to stop rain and possibly flood water coming through the block work. You could add cladding to the outside but that won't reduce flood risk. On the inside the choices are a paint on like bitumen or tanking slurry or a plastic membrane, either DPM or a proprietary tanking membrane. Whatever you use you have to be careful to seal it to the slab and seal any fixings for stud work . For a diyer I would use bitumen or tanking slurry as sealing to the floor will be easier. Once you've done that you don't need an air gap behind the insulation. OSB is considered vapour impermeable so you don't need an additional vapour barrier though it's best to leave a 5mm gap between sheets and then mastic the join.


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## niall Y (6 Oct 2022)

Goesbysteve said:


> oh I can imagine all sorts not done right here. they painted the breeze block with “something” rather than render or glad it. I’m still to work out what the black paint from top to bottom of walls actually is. I’m going to have an exploratory dig around the rear at the weekend. Assuming rain holds off.


You should be able test the coating by burning an area, The smell will be quite distinctive. Many years ago, I was working on a property in Norfolk and we used Ness Synthaproof to paint the barge boards on the roof. It was also used to paint the Cob outbuildings to keep them waterproof


Goesbysteve said:


> If I understood you correctly the walls were painted with black jack on the inside? What was on the outside out of interest?


The Black Jack was applied to the inside - two coats to the concrete blocks, The outside is rendered


Goesbysteve said:


> I definitely want OSB 3 as the inside surface and my budget is only going to reach to rock wool I think. I believe a 50mm airbag between inside of wall and insulation is required if regs applied here. I may only get 25mm and 50mm insulation with 12.5mm OSB over it So I don’t lose too much space. I’m on my getting the rear half as a workshop and the rest is storage and supplies. E.g. two extra fridge freezers.


I have OSB on the walls of my workshop, and it has survived a couple of 'flash floods'. Slight discolouration, but nothing a coat of paint couldn't disguise


Goesbysteve said:


> was the polythene sheet a vapour barrier? I’m not sure I’d be producing enough moisture that could escape through rock wool and get drawn out by airgap. However on the walls I’m not sure how a threw flow is achieved as it would be in my loft.


The polythene covered all the walls, behind the plasterboard and was taped to the polythene Radon barrier covering the floor.


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## Goesbysteve (6 Oct 2022)

Jones said:


> As there's no cavity in the wall you will need to do something to stop rain and possibly flood water coming through the block work. You could add cladding to the outside but that won't reduce flood risk. On the inside the choices are a paint on like bitumen or tanking slurry or a plastic membrane, either DPM or a proprietary tanking membrane. Whatever you use you have to be careful to seal it to the slab and seal any fixings for stud work . For a diyer I would use bitumen or tanking slurry as sealing to the floor will be easier. Once you've done that you don't need an air gap behind the insulation. OSB is considered vapour impermeable so you don't need an additional vapour barrier though it's best to leave a 5mm gap between sheets and then mastic the join.


Thanks I’ll need to go research tanking options! Anything wrong with bitumen paint up the wall outside?


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## Goesbysteve (6 Oct 2022)

niall Y said:


> You should be able test the coating by burning an area, The smell will be quite distinctive.



Thank you, I will try to test this weekend when I do more photos and have a dig,


niall Y said:


> Ness Synthaproof



love the name!


niall Y said:


> The Black Jack was applied to the inside - two coats to the concrete blocks, The outside is rendered
> 
> I have OSB on the walls of my workshop, and it has survived a couple of 'flash floods'. Slight discolouration, but nothing a coat of paint couldn't disguise
> 
> The polythene covered all the walls, behind the plasterboard and was taped to the polythene Radon barrier covering the floor.


Thanks. Very much. Any reason you didn’t go the tanking slurry option suggested elsewhere?


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## Spectric (6 Oct 2022)

Have you thought of harnessing the power of that river to produce electricity?


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## Jameshow (6 Oct 2022)

Goesbysteve said:


> Thanks I’ll need to go research tanking options! Anything wrong with bitumen paint up the wall outside?


If the inside is dry I'd think you can put closed cell foam against the brickwork and it will remain dry? 

It's a garage after all.


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## Goesbysteve (7 Oct 2022)

Spectric said:


> Have you thought of harnessing the power of that river to produce electricity?


Interesting thought, watch this space! Lol


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## Goesbysteve (7 Oct 2022)

Jameshow said:


> If the inside is dry I'd think you can put closed cell foam against the brickwork and it will remain dry?
> 
> It's a garage after all.


My understanding is the wall inside will be cold in winter at least and therefore any moisture going through to it would condense. Thst said if installed right PIR with a foil layer is a decent vapour barrier so little should get there however it’s not a perfect barrier and I’m not a perfect installer either!


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## IBmatty (7 Oct 2022)

As described it’s sounds not that different to one of the ”dependences” that came with my house here in France, although your roof timbers are in a considerably better condition that the ones I had to rip out. It’s on a slope and on one side there is a water risk down to a “déviateur d'inondation”. The local town hall paid for the wall (15mm block) facing that to be protected with an external cladding of 75mm insulation (kingspan/celotex type), glass mesh and finish render. I watched and learned and copied for the rest of the building and DIY’d it. Cost for my bit worked out about 18-20euro per m2 all in, this was 7-8 yrs back. The part of the insulation board underground was lined with a dimpled semi-rigid plastic that is bought in rolls here, not fixed, just held in place by the backfilling. I simply painted the inside walls with an exterior grade masonry paint. Use it for metal workshop and metal storage now, warm and cosy, dry as a bone all with no loss of space inside.


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## Goesbysteve (7 Oct 2022)

IBmatty said:


> As described it’s sounds not that different to one of the ”dependences” that came with my house here in France, although your roof timbers are in a considerably better condition that the ones I had to rip out. It’s on a slope and on one side there is a water risk down to a “déviateur d'inondation”. The local town hall paid for the wall (15mm block) facing that to be protected with an external cladding of 75mm insulation (kingspan/celotex type), glass mesh and finish render. I watched and learned and copied for the rest of the building and DIY’d it. Cost for my bit worked out about 18-20euro per m2 all in, this was 7-8 yrs back. The part of the insulation board underground was lined with a dimpled semi-rigid plastic that is bought in rolls here, not fixed, just held in place by the backfilling. I simply painted the inside walls with an exterior grade masonry paint. Use it for metal workshop and metal storage now, warm and cosy, dry as a bone all with no loss of space inside.


Thanks, very interesting. The glass mesh, is that fibreglass mesh? Was that to provide structural rigidity? I think I may be just too damn close to the secondary tributary on one side to do anything there. I’ll need to show photos of that as it won’t be obvious from the photos I’ve posted so far.


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## david.tamlaght (7 Oct 2022)

Spectric said:


> Have you thought of harnessing the power of that river to produce electricity?


Deep pockets and a very tick skin required in dealing with this issue.
Planners ,rights of access unless you own the stream,water agencies etc,cost of connection to the grid unless you intend to store power for your own use only which is also costly .A small wind turbine on your own patch and some solar panels would be a more realistic option
I ve been involved in this side of things and the figures are eye watering to say the least .Not for the faint hearted to install a water turbine and you can't just lower it into the stream .major engineering job


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## johna.clements (7 Oct 2022)

Goesbysteve said:


> I was thinking the same but living in a conservation area may cause issues even when it’s unseen by anyone and the garage is hardly in keeping.
> 
> There is a fairly decent stone bridge 50m away downstream. It’s field upstream and not woodland though it only takes one tree. I think the flood defences on the door plus suitable waterproofing on outside of walls would be the best I can do. Is Black Jack high up the wall enough for that?


I would have thought that a row of blocks (to match the garage) or paving slabs (to match local stone) to retain the 300mm of soil next to the garage would be considered gardening. I am no expert in planning law. When the garage was built it is unlikely that the soil was supposed to be piled up against the wall so the plans that the council has will reflect this. You will be just doing some gardening to return it to the design condition. 

The plans may be available on the councils website if the garage was built in the last few years. If not do not ask,you do not want them to investigate.

If the road over the bridge is lower than your garage then any flash flood should drain quickly. If a tree in the bridge would cause water to back up to the garage I would make sure I have the flood authorities number to hand and make friends with the local farmers who own JCB type machines.

I assume that the garage is the dark building behind the for sale sign. I also assume that the dark line between the garage and the building with the for sale sign is a small stream. The two culverts that flow under the road are likely to get overwhelmed in a flash flood, I would assume that the water flows across the road once or twice a year. They would be very dangerous to try to unblock from inside the stream.

I would put two coats of black jack plus your door defenses. You already have your electric coming down rather than up so I assume that some thought has gone into flood resilience to the garage.


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## Goesbysteve (7 Oct 2022)

johna.clements said:


> I would have thought that a row of blocks (to match the garage) or paving slabs (to match local stone) to retain the 300mm of soil next to the garage would be considered gardening. I am no expert in planning law. When the garage was built it is unlikely that the soil was supposed to be piled up against the wall so the plans that the council has will reflect this. You will be just doing some gardening to return it to the design condition.
> 
> The plans may be available on the councils website if the garage was built in the last few years. If not do not ask,you do not want them to investigate.
> 
> ...


Thanks thats very useful. I’m certainly not the only resident liable to flooding here and the farmers use the bridge to get between fields. I think that should be dealt with fairly quickly.

I’m going to check my records passed to us on purchase and a light investigation with council, as you I don’t want to trigger an investigation.

I’ll take some more photos when the rain stops over the weekend to show things better.

l’ve started to research flood defences. Designs seem to be very similar between manufacturers for entranceway boarding. The two external doors on the house will be the priority though. I may invest in a flood “snake” that automatically expands when in contact with enough water. That might afford some small flood mitigation. The workshop build inside will not start for a while now. Maybe spring.

I really appreciate your thoughts and advice.


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## johna.clements (7 Oct 2022)

Goesbysteve said:


> Thanks thats very useful. I’m certainly not the only resident liable to flooding here and the farmers use the bridge to get between fields. I think that should be dealt with fairly quickly.
> 
> I’m going to check my records passed to us on purchase and a light investigation with council, as you I don’t want to trigger an investigation.
> 
> ...


I have had little involvement in building but I think that you should take into account the wall thickness is only 100mm on your chosen flood defence. obviously a thinner wall will not be able to take as great a depth of water as a thicker wall.

I assume that the the building (old mill?) at the bend of the river is most at risk.


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## Goesbysteve (7 Oct 2022)

johna.clements said:


> I have had little involvement in building but I think that you should take into account the wall thickness is only 100mm on your chosen flood defence. obviously a thinner wall will not be able to take as great a depth of water as a thicker wall.



im not sure I follow.the metal or plastic barriers are specially made for doorways and garage door ways.


johna.clements said:


> I assume that the the building (old mill?) at the bend of the river is most at risk.


He says the same but has an 450mm wall built against river at the edge of his patio. However riverside ground lowers towards the front of our property to the stream at our side. So technically we are lower than the mill.


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## clogs (7 Oct 2022)

just to add, this stuff works very well for underground wall protection.....along with suitable drainage....





Thats a stunning part of the world.....


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## Goesbysteve (7 Oct 2022)

Flood warning in place here. Interesting timing.

I took some more photos and made a closer inspection rather than relying on my memory. The rear quarter of the garage is probably under more like 500mm. It was starting to hammer down with rain again so I haven’t measured i just looked along the wall and counted courses.











it may not be clear from photos just how close the left hand side is to the smaller stream both in lateral and level.






Also how close the rear of the garage is to the heating oil tank. If built now it wouldn’t be to refs due to proximity. It certainly makes any construction very difficult as I can’t risk subsidence under the tank’s slab. I think that’s beyond diy skill, certainly mine. I think that includes to paint the wall down below the current ground level.






The silver lining is I have confirmed there is a DPM sheet on the garage slab although it is also well underground toward the back.






There appears to be a drain from the underground wall of the rear into the stream but that would t help if the level of that water rose above it. I will do an explorative dig to see if there is evidence of gravel against the wall. I’m also going to try to find details of who built the garage. that might get me more details but I estimate a decade has passed.






I am yet to test the paint used to see if it is bitumen but it looks very matte and thin in depth to me.

Talking further to neighbours water has not come to more than lapping at the gravel access road that immediately boarders our driveway. Maybe 15m from the from of our garage. I will try to estimate/measure the rise from there.


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## Goesbysteve (7 Oct 2022)

clogs said:


> just to add, this stuff works very well for underground wall protection.....along with suitable drainage....View attachment 145008
> 
> 
> Thats a stunning part of the world.....


Is that to be stuck to the wall? Do you have a link I can read more about it?

it is indeed stunning, both this part of Wales and this particular village. It’s in a conservation area though outside the National Park. That may still mean I end up requiring permission in order to do any works on the outside, even the cladding I want to add. Has to improve the look over painted breeze blocks right?


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## johna.clements (7 Oct 2022)

Goesbysteve said:


> im not sure I follow.the metal or plastic barriers are specially made for doorways and garage door ways.


I would say you want one for a garage door way rather than a house door way. (if they make them differently). The thicker the wall the more lateral load that it can take.


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## Goesbysteve (7 Oct 2022)

johna.clements said:


> I would say you want one for a garage door way rather than a house door way. (if they make them differently). The thicker the wall the more lateral load that it can take.


well the ones I looked at were specially designed for double garage doorways and businesses. So I kind of hope they are. I’m not thinking of putting several house door way ones together lol


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## johna.clements (7 Oct 2022)

Goesbysteve said:


> Flood warning in place here. Interesting timing.
> 
> I took some more photos and made a closer inspection rather than relying on my memory. The rear quarter of the garage is probably under more like 500mm. It was starting to hammer down with rain again so I haven’t measured i just looked along the wall and counted courses.
> 
> ...


The blocks including joints are 225 high by 450 long. So there is about 675 depth of soil above the garage floor at the down pipe.

In the last photo there is the pipe which looks like the end of the down pipe and a lower corrugated pipe. I would guess that the corrugated pipe is a land drain running around the back of the garage. I would leave everything as it is and not do any digging. The corrugated pipe may have stone or coarse sand around it with a textile membrane to stop contamination by the soil. If the stone / sand gets contaminated it will not work as well.

Also you have the gas line from your propane tank. A bit of a pain if you have to get that fixed.

I do not think that there is anything you can do at the rear of the garage that would be easy.


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## Jameshow (7 Oct 2022)

Goesbysteve said:


> well the ones I looked at were specially designed for double garage doorways and businesses. So I kind of hope they are. I’m not thinking of putting several house door way ones together lol


How much are they? 

Surely you could make them out of 18mm buffalo board?


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## Goesbysteve (7 Oct 2022)

johna.clements said:


> The blocks including joints are 225 high by 450 long. So there is about 675 depth of soil above the garage floor at the down pipe.
> 
> In the last photo there is the pipe which looks like the end of the down pipe and a lower corrugated pipe. I would guess that the corrugated pipe is a land drain running around the back of the garage. I would leave everything as it is and not do any digging. The corrugated pipe may have stone or coarse sand around it with a textile membrane to stop contamination by the soil. If the stone / sand gets contaminated it will not work as well.
> 
> ...


No that was my assessment too. whilst getting dinner out of the overflow freezer in there I checked around for any sign of water or damp. We have had a lot of rain last few days. No visual sign of damp. Only thing I found was some concrete/cement mortar break up along the inside rear between the wall foot and the interior floor. Only a localised area affected maybe a few 5-10cm patches over a length of a metre. It’s part of the cement that runs all the way round so I assume the bonding between wall and floor. I’m no builder as you can tell. No sign of similar damage anywhere else I could get access to easily. The floor and wall look in excellent condition. No cracks on the floor.

This is turning out to be the project that keeps giving!

Tomorrow I’m going to give it a poke to see if it’s just the surface And try my moisture meter in it. Is patching this a good idea? I may wait for a drier week though there is no moisture in there or around it I can see or feel.


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## Goesbysteve (8 Oct 2022)

It’s just some surface crumbling. Had a friend in the trade coming look. His view was also leave well alone, it’s a well build garage and dry as a bone inside. He discovered there is a thick plastic barrier all the way round the wall at ground level, rising up the wall as the ground rises. There is also a second French drain on the long side where the ground rises to the rear.

super news!


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## Goesbysteve (13 Oct 2022)

Having been distracted by the flood issue for a bit, and being under the weather, I’m now back at worrying about putting 7 x 12.5mm 29kg each plasterboards up on my bottom roof truss. If I sistered the rest of my 2x3s with c24 would that actually make a difference or just add weight on the existing truss structure with no benefit to weight bearing? How would I get 3m lengths up there anyway, I’ve seen folk put them up in two lengths with a bolted metal plate through new and existing. Do they need to go the complete length of existing truss bad onto wall plate? I think there are metal “hangers” that the existing wood fits in, what are my options for ensuing the new sistered wood is flush against the existing?

Is that just a naive view of structural design? Actually I think I know the answer to that latter question!

On my walls I still plan fixing PIR to battens abs taping then boarding over with 12mm MDF. I want to put shelves up using 2x3 or 2x4 near free standing structure screwed into wall. Worried about the screws piercing the foil on the PIR. Do I need to be? is there a fixing method I can use that won’t risk that?

Sorry if this appears to be going over ground ore previously answered. It’s just my reading of other similar plans and replies alternating between “don’t they weren’t designed for it“ and “oh plenty do it just throw some chipboard up there and store a car engine.”

Thanks in advance.


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## Colin the helper (4 Jan 2023)

I


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## d3m0n (5 Jan 2023)

Following, I have a similar predicament in terms of the roof; also having moved recently into a fairly new build (2007-ish) with a separate garage that i would like to "workshop". Our garage roof is almost identical structurally and would also like to board out for storage and then plasterboard. I was also thinking of running extra material the width but didn't think i could without reinforcing the hangers, but the more I look into it common sense says don't bother and just board over it tie it all down and you will be ok, but then the flip side is can those hangers hold all the additional weight of the board, the plasterboard and whatever I end up putting up there (likely more wood + other household goods (Xmas stuff, my fishing gear, etc))


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