Author Topic: damp-proof treatment for exterior single brick  (Read 736 times)

damp-proof treatment for exterior single brick
« on: July 14, 2020, 11:38:07 am »
My daughter was looking at buying a house - it has been surveyed (for different buyer) and they reported that one exterior wall was damp and remedial work would be about £6500.

It is single brick and the damp wall is the end wall (end of terrace house).  Overshadowed by trees, it wouldn't get any sun.

I can't go to see the property, but looking at pictures (which don't show the wall), I guess that that the mortar has crumbled.

My guess at remedial work is:
Rake and regrout wall (two story small end terrace)
Inject DPC
Treat wall with water repellent coating like this: https://www.amazon.co.uk/Enviroseal-Water-Repellent-Penetrating-Treatment/dp/B007796E7A


Not dirt-cheap work, but £6500 seems an over estimate.

It might be that the brick has started crumbling, in which case £6500 sounds too low.

Feedback from people?
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Re: damp-proof treatment for exterior single brick
« Reply #1 on: July 14, 2020, 11:51:59 am »
Where in the country is this?

Re: damp-proof treatment for exterior single brick
« Reply #2 on: July 14, 2020, 11:54:36 am »
When you say single brick do you mean a 9" solid wall?  These are common in certain parts of the country and not necessarily prone to moisture ingress. I would strongly advise against using any silicone treatment externally as this could cause damage to the brickwork in future due to the freeze thaw cycle depending on the brick.

Have rainwater goods and down pipes  been checked?
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Re: damp-proof treatment for exterior single brick
« Reply #3 on: July 14, 2020, 12:00:50 pm »
Location: York

I suspect that this is honestly a single brick thickness wall - not a brick-length thick solid 9" wall.

Haven't seen the property, but survey said it was damp on exterior wall, not rising damp   
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Re: damp-proof treatment for exterior single brick
« Reply #4 on: July 14, 2020, 12:08:33 pm »
 A half brick wall will let by eventually particularly where the rain index is high. (Although the Vale of York is not especially high). The trees don't help if preventing sunlight. A quick chat with building control ref external insulation/cladding/render may be useful particularly if the wall could simply dry out thereafter?. Affected plaster internally may  require replacement with render and possibly other components. Given the Government announcing new grants for insulation etc there may be a possible route here? Does the roof line project or is it flush?  Difficult to judge the £6500 estimate without details but any scaffolding and VAT will swallow a chunk or the surveyor may have had an internal lining in mind. Be careful, lots of cowboys in them there hills.
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Re: damp-proof treatment for exterior single brick
« Reply #5 on: July 14, 2020, 01:19:33 pm »
Get some competing quotes for the work?

Re: damp-proof treatment for exterior single brick
« Reply #6 on: July 14, 2020, 01:55:56 pm »
this is pre-purchase stage, so getting quotes is difficult. I'm not even certain what work is required.

No roof overhang (end of terrace end wall).

Internal lining might work, but you are talking quite a bit of work there - which would account for the 6500
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Re: damp-proof treatment for exterior single brick
« Reply #7 on: July 14, 2020, 01:59:37 pm »
I'd imagine it unlikely to be a single (half brick) thick wall for a two-storey gable wall.  Likely to be a full 9" brick length.  Rake out and re-point would be a good start. 

As per previous comment, avoid exterior silicon sealants and replaster inside with lime plaster/breathable paints rather than gypsum and modern emulsion to let the wall breathe. 

Insulation layers with a vapour membrane may fix it BUT need to be designed to avoid interstitial condensation.

Re: damp-proof treatment for exterior single brick
« Reply #8 on: July 14, 2020, 02:20:00 pm »
10 years ago, West Midlands.  1930s semi with 9" walls, rendered.  I had the front and side treated.  I went on tour for a month and gave the keys to a local builder who lived in an identical house a few yards  away, you might say he project managed it for me.  To ease the job I stripped the wall paper in the affected room and hallway and lifted the floor along the wall so that the injection could be made from inside.  The builder arranged injection, relaid the floor, replastered as needed, fitted new skirting boards and then got a painter to paper and painted ready for when I got home.  About £3500.

Re: damp-proof treatment for exterior single brick
« Reply #9 on: July 14, 2020, 04:40:10 pm »
Which direction does the wall face?  Is it the direction rain arrives from?  Is it rising damp?

Generally brick walls need to dry so if the tree is creating a damp environment that would not help.  I used silicon on a house in Suffolk where bricks are soft and porous and it worked very well despite excruciatingly cold winters in the early 80s. 

On two stories I would be amazed if it was not a 9 inch wall.  You could tell on an older house because the courses would not have half-bricks a.ka. headers showing if it was single skin.  The picture shows what I mean.


Sic transit and all that..

Re: damp-proof treatment for exterior single brick
« Reply #10 on: July 14, 2020, 04:54:43 pm »
West-facing wall, completely under shadow of large tree.

I can't see a picture of the wall in question, however the other house walls look to be single-brick to me. No headers visible.

The advert is here https://www.rightmove.co.uk/property-for-sale/property-81497401.html
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Re: damp-proof treatment for exterior single brick
« Reply #11 on: July 14, 2020, 05:47:51 pm »
If it's not rising damp will a DPC actually do anything?
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Re: damp-proof treatment for exterior single brick
« Reply #12 on: July 14, 2020, 06:11:14 pm »
As others have said it would be remarkable if it was four & a half inch, especially two storeys. 

External sealing will not help. 

Get a specialist in old buildings to look at it.  If there's no mould on the walls, no rotten skirting, no blown plaster, then the diagnosis is wrong.  The standard two prong damp-meters are designed for wood.  Salts in old plaster will give a false damp reading. 

Check the ground level outside.  It should be below the damp-course, ideally 6" or more below.  Damp-course might be slate if it's Victorian, but should still work.

Some useful info:  https://www.homebuilding.co.uk/advice/how-to-treat-damp


Re: damp-proof treatment for exterior single brick
« Reply #13 on: July 14, 2020, 06:14:38 pm »
Looking at the photos, it's a 9" wall.  That garden wall against the house won't help. 

Re: damp-proof treatment for exterior single brick
« Reply #14 on: July 14, 2020, 06:18:26 pm »
With my bricklayers hard hat on I would say that house is constructed with two leafs of bricks with no cavity . A  9" solid wall built using English garden wall bond . If you look closely you will see one course of headers ( Bricks layed across the wall to tie the two leafs together )  followed by five course of stretchers . My attention is drawn to the boundary wall which looks to be but butted  to the house wall . A vertical damp proof membrane should have been installed when built  ( it may have failed )  or better still an air gap of around 50 mm with top sealed  with a lead tray . But its all a guessing game with out seeing the gable end . colin   (cross post with Ian )
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Re: damp-proof treatment for exterior single brick
« Reply #15 on: July 14, 2020, 07:21:46 pm »
There are no internal photos of the gable wall so cant see the location or level of 'dampness'. Condensation may be an issue. Clearly quite a lot of work has been done on the dwelling in the past. A concern would be the formation level of the adjacent car park relative to the gable wall of Wrays cottages and the close proximity of those trees although difficult to tell from a Google view just what the situation really is on the ground.  The Front of the house has been repointed. Has the gable?  Note the air bricks installed in adjacent dwelling. Static air behind fixtures and fittings could be a cause of condensation. Dry lining/insulation is available but reduces room size. Thermal 'wallpaper' linings are available which help. Positive pressure ventilation systems are available (its a fan and vent at the top of the stairs) with minimal annual running costs.  I would want to see the floor where the washing machine was as it looks a bit odd on the photo but could be someone's attempt at levelling the screed for white goods. Where is the boiler and is the stairwell heated? What kind of Boiler/heating? Any pinholes in the circs? What is the ground floor surface material?

Our first home was a two up and two down  stone built house with stone flag floors situated on an exposed hill in the peak district and you could see daylight through the walls when we bought it. If the 'dampness' issues can be resolved don't see why this property cannot be suitable. I don't know what the market is like in York but expect house prices to fall during the next twelve months due to unemployment rising so watch the price to equity ratio and of course any expenses. How the duty changes will impact is yet to be seen.
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Re: damp-proof treatment for exterior single brick
« Reply #16 on: July 14, 2020, 07:34:00 pm »
How long has the house been empty?

How did the surveyor find the damp?  Damp meter?

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Re: damp-proof treatment for exterior single brick
« Reply #17 on: July 14, 2020, 07:38:41 pm »
West-facing wall, completely under shadow of large tree.

I can't see a picture of the wall in question, however the other house walls look to be single-brick to me. No headers visible.

The advert is here https://www.rightmove.co.uk/property-for-sale/property-81497401.html

End cottage....

Looking at the photos, it's a 9" wall.  That garden wall against the house won't help.


I'd want to see how the walls are jointed.

Re: damp-proof treatment for exterior single brick
« Reply #18 on: July 14, 2020, 09:14:59 pm »
So, using streetview which is linked on the details I took a look at the brickwork at the front and the brickwork along the small row including the wall at the other end of the row.

It appears to me that there are a number of courses there is a row of headers.  It doesn't look like classic English Bond but similar implying a 9 inch twin leaf wall.

I like those rounded corner bricks.

Edit:  Just seen canny colin's post.  Ah, English Garden Bond.    :thumbsup:

Re: damp-proof treatment for exterior single brick
« Reply #19 on: July 14, 2020, 11:05:28 pm »
Wasn't this area flooded when the pumping station failed a year or two ago? That'd cause a good bit of damp!

Re: damp-proof treatment for exterior single brick
« Reply #20 on: July 15, 2020, 12:21:19 am »
Avoid “damp specialist contractors” they are targeted by how much silicon fluid they can inject plus replacement timber they can sell.

Canny Colin has made a good analysis, but do use traditional materials for repair. Lime mortar, (not modern cement mortar), lime based plaster to allow the wall to naturally “breathe” and condensation can then escape through natural porosity from the inside to the exterior.

The butt jointed garden wall is a concern and there is likely to be transmission of moisture downwards from this.

The external visible house wall is indeed “English Garden Wall” bond brickwork so 9” or about 230mm likely thickness solid wall. Normal for that age of house. Agree the opposite end of terrace looks to be this too, on street view but would require confirmation by examination.

The damp proof course should protect any internal and underfloor / other timbers and normally be 150mm above external ground levels.

Plus NEVER paint “waterseal” onto external brickwork. Extermely bad idea.

If I were in York I would offer to take a look but regret I am not.




Re: damp-proof treatment for exterior single brick
« Reply #21 on: July 15, 2020, 02:41:22 am »
MrCharly are you local to York? No comment on the damp but that house is really close to Bell Farm estate which has always had a terrible reputation. Possibly the worst place in York for theft etc unless its changed a lot in the last 10 years. Used to be on Mrs Pcolbecks patch when she was a social worker.
I think you'll find it's a bit more complicated than that.

Re: damp-proof treatment for exterior single brick
« Reply #22 on: July 15, 2020, 03:22:38 am »
You can check out crime stats (or how ineffective your local police are) in any area. Google will provide relevant sites to check for such things.

Re: damp-proof treatment for exterior single brick
« Reply #23 on: July 15, 2020, 07:33:24 am »
Avoid “damp specialist contractors” they are targeted by how much silicon fluid they can inject plus replacement timber they can sell.

Canny Colin has made a good analysis, but do use traditional materials for repair. Lime mortar, (not modern cement mortar), lime based plaster to allow the wall to naturally “breathe” and condensation can then escape through natural porosity from the inside to the exterior.

The butt jointed garden wall is a concern and there is likely to be transmission of moisture both possibly upwards and downwards from this.

The external visible house wall is indeed “English Garden Wall” bond brickwork so 9” or about 230mm likely thickness solid wall. Normal for that age of house. Agree the opposite end of terrace looks to be this too, on street view but would require confirmation by examination.

The damp proof course should protect any internal and underfloor / other timbers and normally be 150mm above external ground levels.

Plus NEVER paint “waterseal” onto external brickwork. Extermely bad idea.

If I were in York I would offer to take a look but regret I am not.

Re: damp-proof treatment for exterior single brick
« Reply #24 on: July 15, 2020, 08:45:08 am »
All good information and feedback, thanks.

I looked but couldn't spot the headers (need better glasses?).

It's all a moot point as the agents have taken it off the market and my daughter decided that they didn't want to face the hassle of a house that might need major work straight away.

She is adamant the being close to areas like Bell farm don't bother her. They've lived in various bits of London that were 'lively' so I guess she has some basis for judging that.

Houses in the lower price range in York are selling like free bread.
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