# Damp in Victorian house dining room



## sammy.se (21 Feb 2019)

Hi All, 

Help needed please. I have a room in my Victorian terraced house, where damp showed up in the last six months. 
This room has an external wall facing the garden, and another wall which originally was external facing, but now joins the kitchen – an extension built 15 years or so ago, before I bought the house.
The other wall is internal facing, to the corridor, and the last wall is adjoining the neighbour’s property. See diagram below.











First thing I saw was damp rising on the neighbour’s wall. I monitored for 6 months, and the damp patch was getting bigger. So I took up the and took up the laminate flooring and removed the skirting board to see what was there.
The damp was rising from the hearth (the chimney breast had long been removed before I bought the house).






Strangely half the hearth was damp (actually, the part that would have been under the chimney breast), and the hearth itself was bone dry.






The wall is not damp, and the chimneys have been removed and capped, so it’s not coming from above.

I took a floor board up, next to the hearth, near the extension wall (C), to have a look.
There is a HUGE amount of mould, and it is very damp.
The room has laminate flooring and is used everyday, so I couldn’t take more flooring up, but took some pictures. 






Looking across to the opposite wall, which is a garden facing wall (A), I see the mains water pipe and gas mains, which turn into the kitchen/extension (wall C).

I thought it was a leaky main pipe, but it could be condensation. I saw no leaks, but water droplets are definitely there. I’m not sure if it’s a slow leak, or condensation.






The other thought is, that the garden facing wall is causing this – the colour of the wall looks dark, which may be damp, and it could have traveling across the foundation walls across to the opposite wall where the hearth is.

Two years ago, I dug the garden down about a foot, because the previous home owners had concreted to over the slate DPC, causing damp on the garden facing wall. That is now gone, but could the damp be traveling across the room, from the garden foundation wall??
Looking at the foundation wall from the inside, it is definitely damp, but I think the slate DPC is preventing it traveling up. 










There is one air brick on the garden facing wall, which was added when the garden was lowered, but I can’t see daylight coming through – it might be a wrong position, too high, or blocked. Maybe airflow is constricted.
It’s definitely open underneath through to wall D, but maybe I need to ventilate wall B (the garden wall)? But how can I do that effectively?

Advice needed please:

1)	Does it look like a leaky mains pipe to you? Or just condensation?
2)	Could it be that damp has travelled across the floor that way?
3)	Should I remove the concrete hearth replace with wooden joists/flooring?
4)	How can I stop this problem?

Many thanks – please let me know if you need more info or photos.

S.


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## sammy.se (21 Feb 2019)

The images are high resolution, if you click them they should show you more detail - thanks!


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## MikeG. (21 Feb 2019)

I'll come back to this later, but I just wanted to say congratulations, this is the perfect way to present your questions about building issues. There are useful drawings, and some excellent photos and explanations. This is an example to anyone of how to ask for technical advice.

Dinner is on the table, so I've no time, but ventilation is obviously an issue, and condensation from a cold unlagged pipe too. More later.


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## MikeG. (21 Feb 2019)

OK, I've had a good look at this, and done my own sketches so I am pretty clear of the lie of the land.

Firstly, you say you've lowered the ground level externally, which is brilliant. It is often the first thing I ask people to do. Can you measure where it is now in relation to the floor, and tell me what the surface is now.

Secondly, we need to establish if there is a leak. Do you have a water meter? If so, turn everything off in the house......all taps, check the shower isn't dripping, that none of the taps are dripping, that the loos aren't dribbling water in (tie up the ball-puffins if necessary, and same with the header tank if you have one). Turn the central heating off. Then watch the water meter closely, and see if it turns at all. You might have to do this over an hour or two, because the movement can be almost imperceptible. If you haven't got a meter, well, it's a lot harder. You'll need to dry and clean the pipe wherever you can access it, but particularly where you suspect a leak. The more you can clean and dry, the better, because you then have to compare the dampness on the outside of the pipe over an hour or two. If it just condensation, then you can expect to find the entire pipe at roughly the same level of dampness, but if it is a leak, that should be concentrated in one area, to start with. You can test for damp with sheets of clean dry toilet paper......just hold them around the pipe for a second, then take them off and examine them. Damp is obvious.

Thirdly, can you tell me about the floor in the kitchen? I presume it is solid?

Fourthly, can you take a photo of your airbrick, and tell me roughly where it is in relation to the damp.

Finally, can you take a good look at the old concrete hearth and chimney base. Would it be possible to remove them? How much access have you got under the floor? Can the flooring be taken up and put back down again afterwards (some laminates just click together).

Two certainties: 1/ even if you have a leak, you also have a condensation issue.
2/ any solution will, at the minimum, involve lagging all those pipes and improving the ventilation.

That'll do for starters.

ETA..........no it won't!!

Can you check outside for downpipes and drains local to the wall of that room, and maybe mark them on the drawing.


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## sammy.se (21 Feb 2019)

That's great Mike, thank you for taking the time. I'll work on this tomorrow and post the answers.

Have a good night, thanks again.

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## sammy.se (23 Feb 2019)

So I've spent today fixing my front door (something else that went wrong), and then taking up all the laminate flooring for further investigation.

I just need to upload the pics and type the answers to the questions above, hopefully by tomorrow morning. More damp discovered unfortunately :-(

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## sammy.se (25 Feb 2019)

MikeG.":16izskyt said:


> OK, I've had a good look at this, and done my own sketches so I am pretty clear of the lie of the land.



Indeed - diagrams help my thought process...



> Firstly, you say you've lowered the ground level externally, which is brilliant. It is often the first thing I ask people to do. Can you measure where it is now in relation to the floor, and tell me what the surface is now.



Garden ground level is about 2cm over the DPC… Here is the background on the garden ground level:


















When I bought the house, the garden level had been paved over twice, with a solid concrete bedding. There was visible damp along the interior walls A, E and corner F. So, I had about 1 foot removed from the garden, to get it low enough below the DPC. 

We hit an issue – the original underground clay soil pipe was fairly close to ground level, much more so than in my father’s Victorian house. It was only a couple of inches below the slate DPC. The builder and I remarked how odd that was, that the original house builders did it that way. (The original clay and cast iron gullies were also high, so we were fairly sure it had been done like that since the house was built).
I had the builder replace the clay soil pipe with a plastic pipe and lower it as much as we could – which was determined by the sewer pipe this soil waste pipe joined into. We could only lower it about 5 cm. I estimate it’s about 20cm below ground level now, because I can see the top edge of the 90 degree bend connected to the waste pipe.






10mm gravel was put along the garden wall perimeter, and over the waste pipe, about 30cm wide, then channel drainage on top of that, along the perimeter of the garden walls. The sandstone paving was laid on a concrete sub-base with full mortar bedding. There is about a 5mm between the channel drains and the wall bricks. Two new air bricks were added, to help ventilation. The plinth is removed up to the drain level. I thought this would be enough to prevent damp. The walls dried up inside, so I thought it had worked, but this weekend, I have found LOADS of damp, above the DPC. Below the DPC is dry!





> Secondly, we need to establish if there is a leak. Do you have a water meter? If so, turn everything off in the house......all taps, check the shower isn't dripping, that none of the taps are dripping, that the loos aren't dribbling water in (tie up the ball-puffins if necessary, and same with the header tank if you have one). Turn the central heating off. Then watch the water meter closely, and see if it turns at all. You might have to do this over an hour or two, because the movement can be almost imperceptible. If you haven't got a meter, well, it's a lot harder. You'll need to dry and clean the pipe wherever you can access it, but particularly where you suspect a leak. The more you can clean and dry, the better, because you then have to compare the dampness on the outside of the pipe over an hour or two. If it just condensation, then you can expect to find the entire pipe at roughly the same level of dampness, but if it is a leak, that should be concentrated in one area, to start with. You can test for damp with sheets of clean dry toilet paper......just hold them around the pipe for a second, then take them off and examine them. Damp is obvious.



Regarding the water mains pipe: I cleaned and dried it, and over the course of 24 hours on a mild day, it remained dry. I have now lagged it, and pulled it a few centimeters away from the beam it was touching. (I think it’s called a girder? The one which supports the joists). I will check again over the next few days, but I’m pretty sure it is not leaking.



> Thirdly, can you tell me about the floor in the kitchen? I presume it is solid?



Yes, it's solid. And I also discovered that the end of the dining room, adjacent to the kitchen is also solid, so the concrete starts in the dining room, from the wall that the water pipe was touching:








> Fourthly, can you take a photo of your airbrick, and tell me roughly where it is in relation to the damp.




Yes, see diagram below, and more photos on the next post.





I lifted the floor boards near wall A to have a look behind the airbricks.
The original airbrick, in the middle, has a lot of paint on it, so air flow is restricted.






Behind it is *very *damp above the DPC. Below the DPC feels drier.









I haven’t checked below floor level of wall E yet – but I assume it’s similar. Will check later today/tomorrow.
I did check corner G, which was also very damp above the DPC, but drier below it:






The clay airbrick, behind the downpipe, opens up to a brick wall/concrete, which I didn't know when it was put in. 




> Finally, can you take a good look at the old concrete hearth and chimney base. Would it be possible to remove them? How much access have you got under the floor? Can the flooring be taken up and put back down again afterwards (some laminates just click together).



Yes, the laminate floor is now removed (the click type).
A few hours with an SDS and I can remove the hearth. I have 50cm access under the floor.



> Two certainties: 1/ even if you have a leak, you also have a condensation issue.


Thanks, I have lagged the water mains pipe now, and will continue to check it for leaks



> 2/ any solution will, at the minimum, involve lagging all those pipes and improving the ventilation.
> 
> 
> 
> ...



Downpipes… Yes, there is a down pipe right outside one of the new airbricks. I re-positioned this downpipe when I built a log store… I (stupidly) didn’t think about the effect this might have.

One last observation. This patio slab near the middle airbrick has been damp for 3 days … I noticed it this morning…


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## sammy.se (25 Feb 2019)

I hit the photo limit. Here is more clarity on the airbrick positions:











Also, there is a bottle gully directly underneath that downpipe (which is why I thought it's a good idea to position the downpipe there).


The joists and girders have been affected quite badly. I think years of damp may have caused this? At some point, after fixing the root cause, I may need to replace some of the beams/girders here:


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## MikeG. (25 Feb 2019)

Again, you've caught me rushing off...... Great photos etc, again.

There's an obvious issue with the downpipe in the corner finishing half way up an airbrick, and discharging into the air. Ideally, that should be brought down to sit on top of the channel with a shoe, or should feed straight into a pipe in the ground. As it is now, there'll be bounce from its discharge, and it's an absolute certainty that lots of water from your roof is ending up going straight into the underfloor void through that airbrick.


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## MikeG. (25 Feb 2019)

Obviously I don't have the normal advantage of seeing this in person, but the fundamentals of dealing with damp apply almost universally. I think you have 2 issues here....an ingress of water probably from the downpipe*, but also possibly from the shingle surrounding the pipe that runs parallel to the external wall (which can act as a sump for all the surface water in the area, and anything that leaks), and then condensation combined with poor ventilation helping to distribute the damp and its ill effects throughout that suspended floor area. Dealing with the downpipe is a quick, cheap and easy solution, and should be your first action**.

* It seems quite revealing that you have areas of damp above the DPC, and not below, which suggests that water is getting in at higher level and is prevented from spreading downwards by the DPC.

** Check carefully that the water runs down inside it, and not down the outside. The latter is a common fault.

One option is to remove the floor and cast in a slab with DPM. Given the other floors have already been done, this is an option, but it isn't what I would be doing. 

Under all options I would be removing the old hearth. It is a cold-bridge, and obviously therefore a place for water vapour to condense. Getting all the joists etc completely clear of masonry (except where they bear on it for structural purposes), will help them dry out. 

I would be maximising the air-flow under the existing floor, firstly by sorting the airbricks (& possibly inserting another) but secondly, by putting either floor vents in where the hearth is now, or, if more drastic solutions are called for, by installing a fan in that same area to force air circulation. I would certainly leave yourself an access into that floor so that you can monitor things, and you might evenmake yourself a hygrometer and check on it every month or so. It will take quite a while for this lot to dry out, but you should see positive changes by the end of the summer.


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## sammy.se (25 Feb 2019)

Thanks Mike - very helpful. I will certainly fix that downpipe asap. Airbricks will be easy to fit also, so I will do that. 

As I was doing the investigations and writing this up, the thought crossed my mind whether I would need to dig out a trench alongside the exterior walls, in order to ensure the channel drain is below the DPC. Do you think that is necessary, or is the current drainage configuration ok? I could probably get it 10cm lower (8cm below DPC) I’m limited by the soil pipe height.

The reason I started thinking this way, is because of the damp in Corner G, it's really wet and a) it's far away from the hearth (no concrete connecting it) and b) it's at the opposite end of the wall to the pipe condensation, and the downpipe/airbrick. Is it feasible that damp can travel that way to that corner?

Regarding your point about the shingle being a sump – that makes sense, but how can I test for that? For example, if I inspect the footings below the DPC, and they are all dry, does that mean the shingle is not the problem?

Thanks again for your answers.


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## MikeG. (25 Feb 2019)

The thing is, given the general garden levels and all the hard landscaping, shingle is still your best answer there. The lower you can get it, the better, of course, and if you can provide a way out for any water that gets into it, so much the better.

I think the complication of damp in your circumstance is that it can travel all around that void simply in the air. It doesn't have to have a solid route to traverse because the air is so damp all it does is condense on cold surfaces irrespective of the source.

Ventilation only works when there is movement, and the fundamental issue you have is that all your vents are on the same wall. This means that when the wind is blowing onto that wall it can't really get into the underfloor void because that would require the air in there to get out....and there's nowhere for it to go. Ordinarily, it would go out of a vent on another wall. This is why I mentioned having a floor vent, or a fan: simply to get the air moving.


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## sammy.se (25 Feb 2019)

Got it, thanks Mike, appreciated. I will crack on!!

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## sammy.se (25 Feb 2019)

Another question: when you say a fan, what kind are you referring to? Like an inline or centrifugal type fan typically used in bathroom extraction systems?

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## MikeG. (25 Feb 2019)

That's what I'd use to start with until you've got the damp under control. It would be a bonus if you had one with a humidistat. Then a little computer fan should do nicely to keep things stable.


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## sammy.se (26 Feb 2019)

Thanks Mike. This job will keep me busy for a few weeks around my day job)... 

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## NikNak (27 Feb 2019)

For what its worth....

Did you lag the pipes yet.? and have you been back and had a look yet.?

The reason i ask is... my old dad (89) had a very similar problem about 2 yrs ago, except his was in the void between the kitchen ceiling and the bathroom above. We ripped up the carpet in adjoining bedroom to lift floorboards etc, and the same as the pictures in the early photos you've displayed, the pipes inc the cast iron black pipe going to the tank in the loft were covered in condensation and water droplets. We wiped them all dry expecting to see where the leak was coming from. Nope.... nothing.

In the meantime he'd been in to see his insurance agent who'd arranged for an assessor to come and have a look. Who then arranged for a plumber to come and 'sort it out'.

Plumber came and looked at it from a different angle. Turned out it was a microscopic leak coming from small section of copper pipe nowhere near a joint, and nowhere near where we were looking. The constant flow of water (albeit small) was causing the pipes to chill, and that against the warmth of the house caused the condensation etc. It was such a small hole the 'spray' of water couldn't even be seen. Not sure how he found it, but thank goodness he did. He cut out the 1/2" of dodgy pipe, replaced it, let it all dry out over several weeks, relaid floorboards, carpet etc, job done.

He showed me the piece of copper pipe that the plumber guy cut out. You had to hold it up to a bright light so see the tiny weeny spec of a hole that was there. Just a flaw in the manufacturing process of the copper pipe that then took years to become a problem. I'll ask him if hes still got it, and if he has i'll take a pic and post back here.

Hope this helps....


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## sammy.se (27 Feb 2019)

Thank you NikNak!
I lagged it three days ago, inspected after 12 hours, and left it undisturbed for 2 days - I will check tonight, and will widen my inspection to other parts of the pipe. Thanks for that info...

There is a part of the pipe that was in contact with cement - I'll inspect closely there in case there was some corrosion. 

How did the plumber even spot that leak? Any clever methods?


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## sammy.se (27 Feb 2019)

The extent of the damp is quite disheartening. I'm resolved to fix all the root causes, which includes digging a channel around the exterior perimeter (as much as I can) to make sure I'm under the DPC. The previous owners also put cement render & pebble dash on the walls, not lime, so I'm going to strip that off and let it breath over the summer, then re-render with Lime (the brick faces will no doubt be ruined, so I will have to re-render to stop more water ingress I presume)

If I don't get this fixed, I won't be able to build fitted furniture against the walls, which is what I want to do.

I'm trying to not even think about the joist and wall plate damage done - one thing at a time. Sigh...


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## toolsntat (27 Feb 2019)

sammy.se":bg7ska6g said:


> How did the plumber even spot that leak?



In the quietest time you can find and with good hearing, turn off all uses of water and listen for a feint sound. Closing your eyes will help.
You may not hear anything notable but after a short time get the stopgap turned off.
You, at this point may be able to hear a difference and that is possibly a leak.
We had this happen behind a wall although the noise was detected and it transpired to be a micro leak on a blanked off branch. This branch was before a newer stoptap off the festered unworkable old original stoptap.
If you want a chat PM me a number 8) 
Cheers Andy


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## sammy.se (27 Feb 2019)

Thank you toolsntat, for the kind offer. I will try that tonight when the family have gone to bed. If I think it's not clear either way (leak or no leak) I will PM you.

Cheers
Sammy


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## MikeG. (27 Feb 2019)

Don't be too downhearted, sammyse. You are doing all the right things, and although it may take a time, you will succeed in the end.


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## sammy.se (23 Mar 2019)

Hi Boschboy, 
I think it's too early to say. I've spend any spare time I have (from the day job & family time) trying to fix the route causes and implement some of the recommendations from this thread (Thanks MikeG and others!). 

So far, I have:

Lagged the cold water mains pipe, the full length
Added a new airbrick, and unclogged two existing vents
Added a fan, with built in humidistat, to aid the airflow 
I have dug a channel around the exterior wall, to the depth of 150mm below the DPC, and added drainage (which required me to find a way to connect it to the gully without having backflow/smell coming through)
Removed the exterior plinth to just above the DPC, which was bridging the DPC (when I removed it, the bricks were quite damp behind it, so I'm glad I did that)
Removed the cement render from the external walls, about 1.5m high. I was really pleased that most of the bricks were not damaged by the render coming off - it never bonded fully, probably because it was added while the wall was damp!
Fixed the guttering, there was a couple of leaks and now it ends tighly against the gully, no chance for splash back against the wall.

phew.

Still a lot to do though:

I need to tidy up the plinth and add a bellcast bead
Need to re-point some brickwork using lime (never used lime before)
Internally, I need to remove the concrete hearth (which is acting as a cold-bridge, as MikeG explained above)
Remove gypsum plaster and foil backed plasterboard (previous owner!!) from the external walls, and replaster with lime
Fix/replace the joists and wall plates which have been damaged due to years of damp
Re-decorate the room.

One day, i hope to have a chance to do some actual woodworking!!  
Seems like all my time and money is going on fixing stuff like this, but I do hope I can do something more fun soon.

I took some pictures of my progress, will post them up later.


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## Phil Pascoe (23 Mar 2019)

Not relevant to your problem, but one to remember for damp in old houses - look where the cast iron downpipes are. More often than not they were fixed with wooden wedges driven between the stones - and they rot. The water then tracks in and downwards. I had only two noticeable bits of damp in a late Victorian house - one wasn't very obvious until I took ceilings down and then I could see the water mark about three feet along the joist.* Fortunately there was no long term damage done. The other was a wooden block built into the wall to carry the fascia and to which the wall plate fastened down to - that had rotted away completely allowing the water to wick through the dust and dirt. From the internal plaster repairs I would imagine that had been a problem for several decades. I could lift the corner of the roof clear of the wall ......... not good for a high house on a hill overlooking the west coast of W. Cornwall. :shock: Six inch fascias on eight inch roof timbers weren't doing any favours, either ................. 
* which was about two feet below the source.


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## sammy.se (23 Mar 2019)

Well that's interesting. I have one original cast iron downpipe at the front of the house. No visible damp problems that I can see but I will have a look tomorrow for any wedges type thingies. Cheers.

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## Phil Pascoe (23 Mar 2019)

Often they have been rendered over and the only water ingress is through a small gap around the mounting bolts so it's not immediately obvious. The wedges can be quite large.


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## sammy.se (6 Aug 2020)

So it's been over a year, and now it's time to get back to solving this problem of damp in the dining room. I’ve did a fair amount of work last year, but this year is the big job – I will no doubt need some advice from your good selves.
All the advice on here has been great – THANK YOU!!! - which I have taken on board and here's what I've implemented so far:



I’ve created a trench around the external wall, to take it to as low as possible, which is almost 150mm under the DPC, but not quite. It’s the best I can do because unfortunately the mains waste pipe is higher than it should be (a problem caused when the house was built). Any lower and the drainage wouldn’t work.
As well as digging the trench, I had to replace the channel drainage with low profile (very short!) channels, and had to create u-bends from the new channel drainage into the bottle gully at the lowest possible point. This was done using flexible waste pipes, rubber grommets and some carefully placed cement. The drains all work and water flows freely into the mains waste. 











I’ve taken off the horrid cement rendering off the external wall, about 1.5 meters high. I wasn’t planning to do more, but please shout if you think I should!






Gutters and downpipes have all been sealed and fitted correctly – no leaks.
Inside, the mains water pipe has been lagged for the entire length.
I have fitted a bathroom extractor fan (with humidistat) under the floor, venting out from the dining room via an airbrick. This has been running for 12months+ now. It is powered from a fused switched spur in the dining room.






These are the next steps, and I have a few questions I hope you can help me with. I’ve taken a couple of weeks off work this month:

*Inside the room: *

Remove the concrete hearth completely from the sub-floor
Remove the mixture of cement render and foil backed plaster board from the walls (yes, cement render with finish plaster on top – previous owner’s attempt to cover the damp)
Remove the rotted floor joists and any rotted floor boards
Remove the rotted skirting boards
Remove all debris/rubble from the subfloor
Build new honeycomb walls to support the new joists where the hearth was, using slate to pack and level the joist where needed.
_QUESTION 1: Should I use a specific type of brick, and what should the cement mix be? (I was thinking engineering bricks?)_


Install new joists matching the existing size (2x4), either replacing the entire length of a rotted joist, or sistering if only a portion of the joist is rotted. New joists will also be laid over the space left by the hearth.
_QUESTION 2: I’m not sure how to deal with the ends of the joists (pic below), and how they should be supported. It looks like they are resting on a wall plate (which is rotten and needs replacing as well). Should I replace like for like with a DPM underneath, or is there a better way, e.g. Joist hangers? 














QUESTION 3: Should I place a DPM (Visqueen) under each joist, to prevent moisture transfer?_


Install 100mm slab insulation (Rockwool Flexi) between the joists, supported by netting
_QUESTION 4: I confirmed with the manufacturer that this is suitable - does anyone have better suggestions? 
QUESTION 5: For the narrow gaps between the joists and the brick walls, I was thinking of using expanding foam, is that OK? _


Install new floorboards (I bought solid timber flooring to match the original, but now I’m thinking I might replace the lot with the green sheet floorboards used in modern construction)
Replace the extractor fan with three PC fans (one for each air brick), powered by a 12v adaptor plugged into a regular socket above floor level I was thinking of using these fans: https://www.amazon.co.uk/dp/B00650P2ZC It's quiet, and a 6 year warranty.
_QUESTION 6: Is there a better way to power these? I don’t like the idea of a plug that has a cable going down through the floor. E.g. would it be better to have a 12v driver installed in the subfloor powered by the fused spur?_
_
QUESTION 7: What wood preservative do you recommend for cut ends of the joists, and should I give everything (new and old joists) a coating of a preseverative?_


Re-plaster the walls with lime (and use a lime paint as well)

*Outside:*

Fit bellcast beading to channel the rainwater away from wall into the channel drainage
Repoint where needed with NHL 3.5 
Remove a rogue airbrick that is bridging the DPC and make good the DPC with slate.


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## sammy.se (20 Aug 2020)

Hi all, quick question:

It's very clear now that the room has been stripped that the air vents are above the internal floor level, which is most likely hindering air flow.

Do you think raising the internal floor level is a good idea? About 80mm will mean the vents are below floor level.




I was thinking of laying treated CLS along each joist to achieve this.

What are your thoughts?
I will be adding some 12v fans under the floor also.

It would mean the kitchen door opening would lose 8cm of height, from 200 to 192cm


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## Fitzroy (20 Aug 2020)

Telescopic underfloor vents likely exist for this reason. We have two in our kitchen.


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## sammy.se (20 Aug 2020)

Obvious now that you mention it! 
Are they effective?

I'll see what's out there.


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## Fitzroy (20 Aug 2020)

It's an old granite house 1875, in the adjoining room (original servants kitchen) there was solid floor with no damp course and was nastily damp. We ripped it up and installed a new insulated concrete one with damp proofing etc. Which says to me there is the opportunity for the floor in this room to be also damp. I have not seen any evidence of damp in the room. The room is 4m long and has two vents on the external wall. So from my statistically irrelevant sample of 1, yes they are effective


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## sammy.se (20 Aug 2020)

Fitzroy said:


> It's an old granite house 1875, in the adjoining room (original servants kitchen) there was solid floor with no damp course and was nastily damp. We ripped it up and installed a new insulated concrete one with damp proofing etc. Which says to me there is the opportunity for the floor in this room to be also damp. I have not seen any evidence of damp in the room. The room is 4m long and has two vents on the external wall. So from my statistically irrelevant sample of 1, yes they are effective


Thank you  the room you describe is similar to my situation...


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## MikeG. (21 Aug 2020)

sammy.se said:


> Do you think raising the internal floor level is a good idea? About 80mm will mean the vents are below floor level.
> View attachment 90631



The vent doesn't have to just be below floor level. I has to be below the bottom of the joist. Therefore you'd have to raise this floor getting on for a foot. As that clearly isn't possible, you either need to lower the vent (that will depend on the external ground level), or put in a periscopic vent, which are cheap and very effective. It should be hidden by the skirting. Cross flow is the critical thing here, so there should be clear open vents on the opposite wall, and a clear air path between.


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## sammy.se (21 Aug 2020)

Thank you @MikeG. (and all). Looks like periscopic vents are the way to go.

Sadly, the 'opposite' vents are perpendicular to these, at the front of the house, so I don't seem to be getting good cross flow. Hence I shall add fans to get the air moving a little


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## sammy.se (1 Sep 2020)

Hi All,

I had been working flat out on the dining room the last couple of weeks (took time off work), so I thought I'd give an update since, well, this is the last thing I 'made', and it may help others stumbling on this thread in future.

As mentioned above, it's been flat out - I wish I had taken more pics but to be honest I just wanted to get on and squeeze every minute from every day. My teenage lads were a huge, huge help as well.

The aim was to remove the hearth, rotten wall (sole?) plates, and any rotten joists. Plus, I would also remove the internal plastering which was the wrong material.
Started off well enough, but I discovered that not only was there bad rot, but also woodworm. While I was here, i decided I would replace the lot - and have peace of mind. This is what it looked like once everything was ripped out:







There had been a catalogue of errors/bad building work throughout the years before:

Concrete render on walls;
Foil backed plasterboard on damp walls;
No DPM at all between wood and masonry;
The hearth, which was a cold bridge, was also bridging the DPC, causing the damp to spread up the walls;

This was all ripped out.
Here's a pic of a socket back-box, that was on a cement rendered damp wall - shows the extent and duration on the damp problem:







The hearth is now also gone - that was 1 cubic meter of cement and clay, all very damp:





Woodworm had spread to the passage as well, quite bad, but very luckily completely localised to one joist (above the un-lagged water mains pipe that attracted condensation, not a coincidence, I'm sure) and some local floorboards. All were also replaced:













With all the joists, wall plates replaced and installed properly this time, I also took the opportunity to install 3 under floor fans to keep the air moving:







This, together with three new telescopic vents, and a much clearer sub-floor, is helping with airflow. (The fans may not do much - some might say it does nothing, but it makes me feel I've done what I can...)

Slab (Rockwool RWA45 100mm) Insulation added, with netting - which is really a backup since the slabs fit quite tight.







So next on the list is re-plastering with lime, and then the cosmetic decorating/flooring etc.


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## MikeG. (1 Sep 2020)

Fantastic stuff, Sam. Well done.


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## Coyote (1 Sep 2020)

That's a heck of an effort. Well done. Loving your improvised duck board walkway.


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## thetyreman (1 Sep 2020)

really interesting thread, thanks for posting.


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## Fitzroy (1 Sep 2020)

I love a rip it all out and have a gander underneath thread! You'll be relieved when it's over knowing you've done the right thing.


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## Linwoodjoinery (2 Sep 2020)

I always say the same thing in my head when I’m working on houses like this ‘good old tradesmen’!!


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## MikeG. (2 Sep 2020)

Well, some "good old tradesmen" built the house properly in the first place. Unfortunately, some of the "good old tradesmen" who followed didn't understand the principles of these older buildings.

(MikeG replying to mikeg!!)


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## Linwoodjoinery (2 Sep 2020)

Yes if I’d known when I’d joined there was a MikeG I wouldn’t have done mikeg and I’ve tried to change it but can’t!


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## MikeG. (2 Sep 2020)

Linwoodjoinery said:


> Yes if I’d known when I’d joined there was a MikeG I wouldn’t have done mikeg and I’ve tried to change it but can’t!



If you send a message to Angie, she'll sort it for you.

Edit..........she clearly has already!


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## Linwoodjoinery (3 Sep 2020)

Yes thanks. Really helpful. Thanks Angie


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## MikeJhn (14 Aug 2022)

I know this thread is two years old, but just wanted to say what an enjoyable read it was, to the OP well done for listening, to MikeG well done for persevering, and to everyone else that had a positive input.


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## sammy.se (14 Aug 2022)

2 years on, I am happy to report zero damp problems after the remedial works 

To anyone reading this, please consider lime Plastering, and fixing the fundamentals before embarking on dpc injection


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## MikeJhn (14 Aug 2022)

Nice to get feedback.

Agree dpc injection is akin to Rising Damp, they are both a nonsense.


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## Flynnwood (17 Aug 2022)

Yes - good thread. And good to hear it's all OK two years on. 

Peter Ward on YT has some vids. He also has a pretty comprehensive website: heritage-house.org which is all about old houses and damp. 

He's a geochemist and geologist.


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