Can I safely remove external render bridging DPC?

[bazanaius]

Hi All,

I have a house from 1900, solid brick walls. I believe the original build was sensible - the DPC is 150mm above the external ground and the internal floor is suspended above DPC level.

I am an amateur, and looking for some advice about what I think was a DIY 'improvement' by a previous owner. When I moved in there was damp registered on one wall of a single room - only very recently have I realised that on the external side of that wall, a concrete render has been applied from ground level up by about 200mm, and so bridges the DPC. I now know that this is most certainly the cause of the damp in that room (although please say if I'm wrong!).

It is just an 8ft section of the external wall - I'm wondering what the repercussions of me chiseling off the top 60mm of the render would be, and whether this would be a satisfactory solution to the damp rising?

From reading, I suspect that the render was used to cover up frozen brick damage - I'm not hugely bothered by the aesthetics of them, but I know they can cause other problems. Is this a reason not to remove the render, am I ok to try it and find out, and if there are frozen bricks behind how quickly must I react to replace/fix them?

Thanks in advance for any suggestions - if this is in the wrong place, please just say and I'll move it.

cheers,

B

 

[roy c]

Put some photos up of the outside wall and also some photos of where the damp is on the inside. It sounds like you have got damp tracking from the outside to inside.But it may also be rising up from below ground level..How long have you had the house and is there damp anywhere else in the house?

 

[bazanaius]

Hi Roy, thanks for the quick reply. See attached some photos and a few answers to your questions - thanks for your help!

- The room in which the damp is has had a dehumidifier running since I moved in. the photo of the skirting board is the wall shown with the low level render outside - no other walls in the same room show the same evidence of damp.
- I've lived in the house for 5 years. I'm not aware of any damp elsewhere in the house. After I moved in this room had the lower 1m of plaster removed internally and some chemical treatment injected into the brickwork before replaster and decorating, so that photo is about 5 years of damp's worth. I'm aware that I should have researched reasons for the damp before attempting a fix... first time buyer, building amateur, lesson learnt.
- I think the floor indoors is higher than the DPC (see airbrick position) - apologies for the photos, it was raining when I took them so sorry if that's confused anything. I'm aware that the paving in the back garden has been laid on top of the original 'ground' outside, so if removing the bricks nearest the wall is something that needs doing that's not a problem; but I'm reasonably happy that the concrete path against the wall with the rendered section is original, or at least at original height.

if there's anything else just let me know!

cheers,

B

 

[bazanaius]

My photos didn't appear in that post... try this.

IMG_20161017_082751

• bazanaius
• 17 Oct 2016

IMG_20161017_082732

• bazanaius
• 17 Oct 2016

IMG_20161017_082714

• bazanaius
• 17 Oct 2016

IMG_20161017_082542

• bazanaius
• 17 Oct 2016

 

[vinn]

OP,
The low level sand & cement plinth needs removing completely from wherever round the house.
You need more air bricks - 10 x 6 plastic a/b's.
The skirting shows spotting - it could be from damp penetration.
Have the sub-area joists that sit in the wall been examined for rot & lack of ventilation?

I dont think that the ground level is too high but then I cant see your DPC (where is it?) to really judge.
Perhaps the bricks should be removed? The air brick below the door is new.
Where does the splash water come from - is the gutter leaking?

Replacing bricks here & there is no big problem or big hurry.

When the damp people re-plastered what material did they use?

 

[bazanaius]

Hi Vinn,

thanks for your reply:

- Thanks for confirming what I thought about the sand/cement plinth; I'm confident (based on other stuff around the house) that this was a DIY cosmetic addition by a previous owner, so I shall remove it. Thanks for confirming that if there's frozen/damaged bricks underneath it is not too urgent that I replace them (although I will ASAP) - i.e. it is better to remove the plinth/render than leave the bricks covered.

- I also struggle to see the DPC myself (will have a closer look tonight), but I believe that it is at the layer of mortar just covered by the sand/cement plinth. I think this means that the path down the side of the house (where the plinth is shown) is probably a bit higher than ideal but definitely below the DPC. However now I'm looking at it more closely the bricks/paving at the back of the house are definitely too high. If I remove the bricks, should I just leave a gap between the paving and the wall (I'd fill in some of it so it wasn't a trip hazard, but make sure it wasn't touching the wall any more)?

- Apologies for my lack of experience - I know that the house is solid brick walls; I presume when you refer to sub area joists you mean the joists that the floorboards sit on inside the house, and the point at which they rest on the brick walls? I can take a look at these tonight; they're quite easy to get to as there are a few loose floorboards.

- The splash water is indeed from a leaking gutter joint; something that was fixed last winter but has re-appeared with the recent rainfall. I'm booking someone in to just replace that joint in the next week or so as it's very high up and I don't have a suitable ladder.

cheers,

B

 

[chappers]

If your house was built in 1900, then there's every chance it wont actually have a DPC. They were using bitumen type products around that time but most houses were built without or in some cases a layer of slate between courses. make sure your ground level is below your airbricks and maybe consider adding a few more.

 

[vinn]

By 1900 most houses had DPC's - introduced under the Public Health Act of 1875.
Its ridiculous to say that the OP's house "wont actually have a DPC" - whats the "actually" being used for, some kind of get-out clause?
Why even say that when the OP has not yet had "a close look"?

"maybe consider adding a few more" air bricks - Well yes, I had already suggested that but I've no objection to you copying my posts much as you seem to copy lumps of google information - perhaps you will learn something?

And its not a "maybe consider" because anyone experienced in this work would take one look at the photos & see the necessity for more & larger air bricks esp. in a damp house.

 

[vinn]

B,
Dont worry about lack of experience in this building trades stuff - its a DIY site.
Just remove the bricks & then post a photo of the result.

Typically, 1900 DPC's were installed just below the joist seats/air brick & sometimes just above the joist seats or the air brick.

Are both walls in the photos affected with damp inside? Can you post photos of the damp?

I still dont know whether render or plaster was used in the late remedial work?

 

[chappers]

By 1900 most houses had DPC's - introduced under the Public Health Act of 1875.
Its ridiculous to say that the OP's house "wont actually have a DPC" - whats the "actually" being used for, some kind of get-out clause?
Why even say that when the OP has not yet had "a close look"?

Not a get out but a caveat as when the OP does look there is a every chance he won't find a DPC. There were still loads of houses built after that time without DPC's I live in such a house, which is a row of 6 all built in 1904 all with no DPC, other houses of similar age in the area have slate DPCs others across town that are older have bitumen DPCs. My point was don't be surprised if you don't find anything.

 

[bazanaius]

Hello All,

just a bit more info before I'm able to get the plinth removed for more photos:

just the wall with the plinth outside shows signs of damp inside - although the wall next to the patio is mostly patio door, so I'll double check when I look at the joist mountings.

When the wall was treated and interior redecorated after I moved in, this was new plaster applied internally to a height of 1m. It had obviously been done before - up to about 900mm it was modern plaster (hard to get off) and above that it was much older plaster that was quicker to come off. I think, Vinn, you're trying to work out whether the plaster applied was breathable and whether incorrect plaster might be causing the problem? Honest answer is I've not got a clue, but if there's anything I can look at to work it out just let me know.

cheers,

B

 

[roy c]

I think by the look off the bricks that most of the faces of the bricks have eroded over time and without the faces it has made the bricks quite porous. Maybe worth getting some prices for having the house rendered or dashed.(lf there are any other houses that have been dashed )Dash will disperse water better than flat render. Have a look around your area and see what other people have done .Even knock on their doors and ask if they have had any problems with damp.Might give you a few ideas....