1steven
Claremorris Ireland
Is that cement as mortar or lime?
Building a workshop in an old stone built barn
- Thread starter David66
- Start date
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So digging the back is out, but I totally agree that guttering is a must. After that it's what I said earlier, I would construct a raised floor and insulate the roof. If, after this, the barn is still damp then build the inner walls using battens, studs and housewrap.
My 2p worth, which I think is what others have suggested (I think your original idea) is to build a building within the building isolated from the structure. I think you are on a loosing battle trying to remedy the damp issue, gutters would help but at what cost and to what level of benefit. You'd loose the lovely aesthetics but the only way to keep those would be a full on renovation £££££, which seems a poor choice as it is not your building you are investing into.
One of the positives of building a structure inside is that you have a good weather screen so you're not really worried about managing water ingress from rain etc. So for example you could look out for a large second-hand double glazed window (free on gumtree) and use it as a skylight facing the transparent roof panel.
You would loose some space internally as I think you would want to leave a good gap at the rear between the damp wall and the new structure, so that the old wall still has reasonable ventilation to/from the roof void. With a 100mm gap and a 100mm stud wall at rear and a 50mmg gap and 100stud wall at front, you've just lost 350mm from the width of the room, is that manageable?
Messing about in sketch-up, some of the things that jump out at me are:
- is the space big enough to enter through the normal door and then have another door on the internal structure.
- do you need access internally to the doorway to the room on the right, it looks like there is another door, so perhaps not.
- you risk creating a fantastic home for wildlife, under or between the internal walls, i was warned of this when I put insulation quilt in the floor of my shed, fingers crossed so far i've been ok, but im urban not rural.
- if you uses screws for construction, you can dismantle and take with you, some cladding on the outside and you have a shed.
- a 4x2 floor with lots of feet to limit span width and hence timber height, dpm under the 'feet' to stop damp ingress into the timbers.
- I would cross batten the internal roof structure for insulation and space for a reclaimed window
- simple 4x2 frame with PIR insulation in floor, walls, and ceiling. Internally clad in your choice, 9mm ply or 11mm osb
- i'd not bother with external building wrap as there should be no water to worry about
- with this approach the cold side of the isulation is very well ventilated to no worry about condensation either
- you may want a couple of LED panels in there the design would reduce the incoming light from the panel
- i think you're looking at c.£2k for materials
Some thoughts, perhaps helpful perhaps not.
One of the positives of building a structure inside is that you have a good weather screen so you're not really worried about managing water ingress from rain etc. So for example you could look out for a large second-hand double glazed window (free on gumtree) and use it as a skylight facing the transparent roof panel.
You would loose some space internally as I think you would want to leave a good gap at the rear between the damp wall and the new structure, so that the old wall still has reasonable ventilation to/from the roof void. With a 100mm gap and a 100mm stud wall at rear and a 50mmg gap and 100stud wall at front, you've just lost 350mm from the width of the room, is that manageable?
Messing about in sketch-up, some of the things that jump out at me are:
- is the space big enough to enter through the normal door and then have another door on the internal structure.
- do you need access internally to the doorway to the room on the right, it looks like there is another door, so perhaps not.
- you risk creating a fantastic home for wildlife, under or between the internal walls, i was warned of this when I put insulation quilt in the floor of my shed, fingers crossed so far i've been ok, but im urban not rural.
- if you uses screws for construction, you can dismantle and take with you, some cladding on the outside and you have a shed.
- a 4x2 floor with lots of feet to limit span width and hence timber height, dpm under the 'feet' to stop damp ingress into the timbers.
- I would cross batten the internal roof structure for insulation and space for a reclaimed window
- simple 4x2 frame with PIR insulation in floor, walls, and ceiling. Internally clad in your choice, 9mm ply or 11mm osb
- i'd not bother with external building wrap as there should be no water to worry about
- with this approach the cold side of the isulation is very well ventilated to no worry about condensation either
- you may want a couple of LED panels in there the design would reduce the incoming light from the panel
- i think you're looking at c.£2k for materials
Some thoughts, perhaps helpful perhaps not.
johna.clements
Established Member
I know the op suggested 4x2 feet to sit the floor on but I think it would be better to use engineering bricks, slate/ quarry tiles.
The existing floor is very uneven with the channels for animal product etc. Square cut 4x2 will in many cases only be resting on an edge or corner. In some cases they could end up in low points so some dpm will not do much good. They will all be different sizes.
If you use engineering bricks, slate/ quarry tiles you can take out all the variation with the mortar under the brick or tiles (depending if it is a high or low spot.) Then put a bit of dpm over each pad and build away off a level surface or a couple of level surfaces to take account of the barn cross fall.
The existing floor is very uneven with the channels for animal product etc. Square cut 4x2 will in many cases only be resting on an edge or corner. In some cases they could end up in low points so some dpm will not do much good. They will all be different sizes.
If you use engineering bricks, slate/ quarry tiles you can take out all the variation with the mortar under the brick or tiles (depending if it is a high or low spot.) Then put a bit of dpm over each pad and build away off a level surface or a couple of level surfaces to take account of the barn cross fall.
mortar
Thanks so much for your input.The width of the building internally is about 3.7m, and around 5m in length - so losing 350mm is probably fine.
I think there is room for an internal door - however, I do need internal access to the far room. So there will need to be 2 doors.
£2k in materials "yikes" ..... !
Thank you all for your advice. Much appreciated.
Looks like I need to make a decision on whether to insulate or not. If not, then a simple raised floor, and maybe a wall to hang stuff on would probably be fine.
Trouble is, there will be 3-4 months of the year where it will be too cold to work in the shed. Also, there may be rust issues with the tools.
If I insulate (and heat) the shed - then an internal room is probably necessary. It would be much more expensive (at least double the cost) more work, and more complexity.
TBH - I dont mind the work and the complexity ... think I might actually enjoy it ... but the cost is an issue - and ... it's gonna look a bit odd!
Decisions decisions
Looks like I need to make a decision on whether to insulate or not. If not, then a simple raised floor, and maybe a wall to hang stuff on would probably be fine.
Trouble is, there will be 3-4 months of the year where it will be too cold to work in the shed. Also, there may be rust issues with the tools.
If I insulate (and heat) the shed - then an internal room is probably necessary. It would be much more expensive (at least double the cost) more work, and more complexity.
TBH - I dont mind the work and the complexity ... think I might actually enjoy it ... but the cost is an issue - and ... it's gonna look a bit odd!
Decisions decisions
johna.clements
Established Member
£2k seemed quite cheap to me.
But since the workshop will be inside and not subject to the wind and snow could the walls and roof use smaller timbers than 2 by 4? Will you need to get on the top of the workshop.
I have seen many offices in box type constructions inside factories and warehouses, nothing odd.
But since the workshop will be inside and not subject to the wind and snow could the walls and roof use smaller timbers than 2 by 4? Will you need to get on the top of the workshop.
I have seen many offices in box type constructions inside factories and warehouses, nothing odd.
Good point - no need to get on top of the box - so would 2x2 for the wall framing work?
Where would the bulk of the costs be - in the wood?
Jameshow
Established Member
I'd make the inner room 3.6m X 2.4m if at all possible.
50mm cavity will be fine.
3x2 will be fine ( and better if you want to use later on) with a 50mm pir / polystyrene insulation building fabric to outside and osb to inside.
Why 3.6m by 2.4m that's a lot smaller than nit could be.
johna.clements
Established Member
I was thinking 4 x2 for framing around doors, corners, windows, where you are going to hang shelves, roof plate and 4 by 1.5 other places in roof and walls.
I estimated about 70m2 of wall, floor and ceiling area. At £40 per 100mm insulation board that £900 of insulation. About £600 for osb and £500 for studs, fixings etc.
You can often see cheap insulation on gumtree etc folks with a board left over after a job. you’ve plenty of space to store it so you could bring that price down with some patience, what your building is never going to be building regs compliant so any old seconds or partial damaged bits would work.
Jameshow
Established Member
Jameshow
Established Member
Sorry I meant 3.6 wide X however long and 2.4 high if possible!
Adam W.
A Major Clanger
Having looked at the pictures, I still stand by my suggestion of getting a wooden shed and not bothering with the stone barn.
Ah... that makes sense. I think I can make it 3.6m wide, and 4.8 long. 2.4 high won't work though. In the words of the late great Meatloaf "2 out of 3 aint bad"!!
Reviewing all the comments there is one thing that I wanted to ask.
Some recommend a double wall, with building wrap on the outside wall, then an internal, insulated wall. Others have said that a single insulate wall would be OK, providing there is a 100mm gap to the rear wall. No need for the building wrap.
What's the thinking behind the double wall method, and what is the advantage/disadvantage (double wall is obviously more expensive)?
Some recommend a double wall, with building wrap on the outside wall, then an internal, insulated wall. Others have said that a single insulate wall would be OK, providing there is a 100mm gap to the rear wall. No need for the building wrap.
What's the thinking behind the double wall method, and what is the advantage/disadvantage (double wall is obviously more expensive)?
My understanding of the whole wall construction conundrum. A workshop wall typically needs to provide two functions, a protection from the weather and insulation to the building. You also have a couple of issues to consider, first how you actually construct the wall so it stays standing and is weathertight before the building is finished, and secondly you need to manage the risk of condensation. With these in mind:
Protection from the weather and the risk of moisture penetration is managed by having a two layer design. An outer layer that should prevent ingress, often cladding on a shed, and an inner layer that any penetrating moisture can drain down to a suitable location. Using building wrap on a shed means that any penetrating moisture is stopped by the membrane from reaching the main structure.
When insulating a building you end up with a warm side and a cold side. The air on the warm side will hold more moisture than on the cold side, so any moist air that moves from warm to cold will drop out condensation. If this condensation occurs in the wall you can get interstitial condensation which leads to damp. This is managed in two ways, normally with a vapor barrier on the warm side between the insulation and the final wall facing, and then providing a ventilated area on the cold side of the wall so that any condensation that does occur can evaporate/dissipate over time.
Building a stud wall and putting osb on the outside of the wall means that you very quickly have a fairly weather proof structure. Additionally it allows you to come back and insulate at a later date from the inside, in dry conditions, which is nice from a construction view point. However, once you come back and insulate you have the risk of interstitial condensation behind the insulation on the interior surface of the external board, which is unvented. Building this way is common practice in some parts of USA and Canada, take from that what you will.
Building with building membrane on the outside, then insulation, then internal boards is beneficial from a cost perspective as it minimises the amount of materials, and is ensures a well ventilated and breathable 'cold-side'. However, until the external cladding/rain screen is in place it leaves the building a bit exposed to damage, as the membrane can be wind damaged and rain can pass into the already installed insulation. Additionally from a wall strength/stability viewpoint you want to get the internal boarding done asap. I'd also say you would be limited to solid types of insulation board rather than any kind of quilt.
Building an internal structure as you have proposed. You do not need to worry about penetrating moisture as the existing building provides all the protection you need from rain etc, and the large gap with no connection to the external walls mean anything that does penetrate will run down the internal surface of the existing walls to the floor. You have less worry over immediate structural strength as again the existing building gives you protection from wind etc. So IMHO you have no need for building wrap nor external boarding, and by going that route you open up the possibility of interstitial condensation.
Sorry essay, but i'm keen to put my thinking out there so others can educate me as every day is a school day.
Fitz.
Protection from the weather and the risk of moisture penetration is managed by having a two layer design. An outer layer that should prevent ingress, often cladding on a shed, and an inner layer that any penetrating moisture can drain down to a suitable location. Using building wrap on a shed means that any penetrating moisture is stopped by the membrane from reaching the main structure.
When insulating a building you end up with a warm side and a cold side. The air on the warm side will hold more moisture than on the cold side, so any moist air that moves from warm to cold will drop out condensation. If this condensation occurs in the wall you can get interstitial condensation which leads to damp. This is managed in two ways, normally with a vapor barrier on the warm side between the insulation and the final wall facing, and then providing a ventilated area on the cold side of the wall so that any condensation that does occur can evaporate/dissipate over time.
Building a stud wall and putting osb on the outside of the wall means that you very quickly have a fairly weather proof structure. Additionally it allows you to come back and insulate at a later date from the inside, in dry conditions, which is nice from a construction view point. However, once you come back and insulate you have the risk of interstitial condensation behind the insulation on the interior surface of the external board, which is unvented. Building this way is common practice in some parts of USA and Canada, take from that what you will.
Building with building membrane on the outside, then insulation, then internal boards is beneficial from a cost perspective as it minimises the amount of materials, and is ensures a well ventilated and breathable 'cold-side'. However, until the external cladding/rain screen is in place it leaves the building a bit exposed to damage, as the membrane can be wind damaged and rain can pass into the already installed insulation. Additionally from a wall strength/stability viewpoint you want to get the internal boarding done asap. I'd also say you would be limited to solid types of insulation board rather than any kind of quilt.
Building an internal structure as you have proposed. You do not need to worry about penetrating moisture as the existing building provides all the protection you need from rain etc, and the large gap with no connection to the external walls mean anything that does penetrate will run down the internal surface of the existing walls to the floor. You have less worry over immediate structural strength as again the existing building gives you protection from wind etc. So IMHO you have no need for building wrap nor external boarding, and by going that route you open up the possibility of interstitial condensation.
Sorry essay, but i'm keen to put my thinking out there so others can educate me as every day is a school day.
Fitz.
johna.clements
Established Member
I assume that the workshop will only be heated whilst in use.
The barn roof looks fairly new so little wind and rain would get in to wet the exterior but there would be no sun and wind to dry it.
I have never used one but would a small solar powered extractor fan lower the moisture level inside the workshop to the general barn level. I know it would not run for long on rainy days in January.
@Fitzroy what are your thoughts on a moisture barrier under the inner boarding.
Not sure what the workshop will be used for but if less mositure gets into the workshop there will be less condensation. I would hang wet coats and boots outside.
The barn roof looks fairly new so little wind and rain would get in to wet the exterior but there would be no sun and wind to dry it.
I have never used one but would a small solar powered extractor fan lower the moisture level inside the workshop to the general barn level. I know it would not run for long on rainy days in January.
@Fitzroy what are your thoughts on a moisture barrier under the inner boarding.
Not sure what the workshop will be used for but if less mositure gets into the workshop there will be less condensation. I would hang wet coats and boots outside.
