Damp walls on extension

[noseall]

I went back and checked some of the things you guys mentioned.

1. I knocked off some plaster on one of the damp internal walls and found the brick also damp:


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2. I took some photos showing more of the outside of the building:


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The internal wall of this side of the building is where the damp goes up around 2+ meters:

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The roofing felt was overhanging, but I could not tell if it would be catching water that could then be getting inside

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3. I was thinking the damp could be being casued by the pebble dash breaching the DPM, but then I noticed that on one side of the exstention building it does not have pebble dash, yet that wall is still damp on the inside.

The wall without peble dash:

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then on the inside of the wall above it looks like this:


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-In the photo above I removed the radiator pipes boxing. I checked for leaks on the pipes but they seemed ok. Yet the wall is very damp, even though the outside of this wall has no pebble dash on it. As mentioned previously, the wall connecting the main building to the extension also has some damp at the bottom of the wall.

It's damp because it's a low end poorly built, zero cavity, zero insulation structure.

It need several thousand quid spending on it, to bring it up to snuff. Just about every façade or elevation need work doing to it.

 

[Deluks]

Do those roof tiles have enough overlap? If water was driven up underneath.....
There seems to be felt, but it's not clear what happens at the verges

 

[DM7]

is there any type of covering that could be put on the internal walls to at least keep it damp-free on the inside of the building? (as a cheaper alternative to sort the issue out for him) and if so, would the dampness underneath it cause any further damage to the extension over time?

He had originally asked me to install damp-proofing rods in the walls, but I said I wasn't sure if it was required and I didn't want him to waste money on things that wouldn't help him sort out the cause problem.

 

[Notch7]

is there any type of covering that could be put on the internal walls to at least keep it damp-free on the inside of the building? (as a cheaper alternative to sort the issue out for him) and if so, would the dampness underneath it cause any further damage to the extension over time?

He had originally asked me to install damp-proofing rods in the walls, but I said I wasn't sure if it was required and I didn't want him to waste money on things that wouldn't help him sort out the cause problem.

What is the wall construction?
Is it solid, cavity. Cavity with insulation?

You could start by clearing all around the outside, maybe removing a foot width of the hard standing and forming a French drain with a perforated pipe discharging into the gully.

Inside I can’t you have any choice but to strip off the plaster, isolate the damp and plasterboard over.

You could just put say 50mm of celetex against the wall, tape all joints, then 50 x25 battens flat then foil back plasterboard.

If you don’t to insulate then there are isolating membranes that can be fitted before re plastering.


I suppose you could fit wall rock dampstop wallpaper over the plasterwork, it’s a bodge but your only other option is stripping the plaster off the wall

Wallrock DampStop Thermic

A technically superior, zero paper and zero tar content liner, Wallrock Dampstop thermic does exactly what it says on the roll, by blocking penetrating damp & staining

coveryourwall.co.uk

 

[DM7]

What is the wall construction?
Is it solid, cavity. Cavity with insulation?

I need to go back and find this out. I'm not sure what the easiest way to find this out is, as I don't think he has the drawings from when the previous owner had the extension built.

 

[catlad]

Its needs knocking down and rebuilding, the dpc whatever it was has gone and its sat in a bog!

 

[DM7]

Hi,

So I forwarded him the info from this forum chat, around the time youse all gave your suggestions, and I gave him a link to this thread so that he could read through all your comments.

I told him its not really a job I wanted to take on, and now I only do plumbing and electrical work, so I wasn't feeling to take on building a tench and doing any of the other things you guys recommended, and I said to him to look around for someone who knows more about this topic, and to see if they can advise and do the works for him.

He messaged me yesterday and asked what I think about putting damp-proofing rods in the wall, but I wasn't sure if they would solve his issue.

Do any of you guys know if they are suitable for the type of damp issue he has?

 

[endecotp]

He messaged me yesterday and asked what I think about putting damp-proofing rods in the wall, but I wasn't sure if they would solve his issue.

Do any of you guys know if they are suitable for the type of damp issue he has?

No.

 

[Deluks]

Just say yes, then block him.

 

[DM7]

Just say yes, then block him.

He is a good guy, though.

It must be around 14 years now since I started working in the trade. And in all those years, I think only 2 customers have ever insisted on paying me more. It often that customers may pay an extra £10 or somthing to round the bill up, but customers who are genuinely good enough to insist that they pay more are rare, even when you underquote a job, customers still usually dont want to pay a fair price, but are very quick to complain if they think you overcharged.....

This guy though, I have worked for him on jobs in his home and his business, for around maybe 8 years, and he is always saying he wants to pay me more, and advising me to raise my prices, lol! complete opposite of most customers... And always offering cups of coffee and home-cooked meals when I'm doing jobs for him at his house. So really can't complain, and happy to help him with anything, even if it's not a trade I normally do, I will make an exception for him (if its somthing im confident in doing), as he is a good guy, and always been good to me. So a lot of respect for him.

 

[DM7]

No.

He messaged me today and said he got a company to do a damp survey last year. He showed me the proposal today. The bassically said they thing he needs a chemical DPC and some other things to solve the problem. I'm not sure if they are scamming him or not, though, as I have always heard bad things about companies ripping customers off with fake claims that chemical injections are needed.. I'll copy some of their proposal below.

The customer is a good guy, very honest, and doesn't deserve to be ripped off (not that bad customers deserve being ripped off, but still worse when it's a good guy having it done to him)

The propsal >>

"
Rising Dampness

At the time of our inspection visible signs of dampness, supported by moisture profile readings obtained with an electronic moisture meter, indicated the presence of rising dampness to some other walls indicated for treatment on the attached sketch.

The rising dampness appears to be due to the failure / deterioration of the existing damp proof course.

Rising dampness is a common, naturally occurring phenomenon caused by moisture rising via capillary action into the building fabric. Most masonry building materials can be subject to rising dampness and, without suitable protection, your property can suffer from the problem. Effects can include unsightly mineral salts, moisture staining to decorative surfaces and, in severe cases, the breakdown of wall plaster due to salt contamination.

Our method of installing a new damp proof course will control rising dampness above the level of the newly installed damp proof course. It will not control dampness below this level.

Plaster & Salts

As the moisture rises from the ground or penetrates from above, into a wall, it carries with it soluble salts which may be deposited in the wall fabric and plaster, as the moisture evaporates. Certain of these salts, in particular chlorides and nitrates, are hygroscopic; that is they are capable of attracting and absorbing moisture from the atmosphere when the relative humidity is high.

Effects

The defects noted from our inspection above will or are likely to allow moisture to be transmitted into the building fabric. Not only is this likely to spoil and damage internal finishes and decorations, but it will also put timbers within the property at serious risk from fungal decay and damage the building fabric itself. We strongly advise that you arrange for all the above noted defects to be attended to.

Recommendations

We have detailed below the items of work that [redacted] will be pleased to undertake for you, together with quotations.

Damp Proof Course

[redacted] are to:

Install a chemical damp proof course incorporating our [redacted] DryWall Diffusion Process to those walls indicated on the sketch, in accordance with the explanatory leaflet attached. Our quotation for this work is enclosed.

Our damp proof course can be installed (subject to access) in solid walls from one side only of the wall to be treated, causing the minimum of disturbance. Non-flammable and non-toxic fluid is used in the installation. There is therefore no fire risk, the property can remain occupied with a minimum of inconvenience to the occupants and will have no ill effects on you or occupants of the adjacent property.

Dry Wall Coating

To control rising dampness in a wall, in addition to the proposed DPC it is of great importance that internal plaster is capable of preventing hygroscopic salts affecting the wall surface, (please refer to our ‘Rising Damp & Re-plastering’ leaflet).

Our recommendations and comments are as follows: -

It is usually recommended that all the walls to be treated are re-plastered to an even height as indicated on the sketch, strictly in accordance with our specification for ‘DryWall Coating’ but as the walls have been dry lined full height we will have to change our specification in places so that our new plaster matches the existing but can still prevent any salt contamination into the finished wall surface.

Our quotation covering re-plastering allows for the following:-

[redacted] are to:-

Hack-off and remove existing plaster from the areas and heights indicated on the attached sketch, and clear resultant debris from site.

Re-plaster these areas in accordance with our specification for ‘DryWall Coating’.

After re-plastering, hairline cracking of the setting coat may occur. This will not present a problem regarding the efficiency of the new plaster and should be made good when decorating.

Upon removal of the existing wall plaster or render it may be discovered that an excessive amount of materials have been applied to bring the wall out to level. Under such circumstances additional labour and material costs will be incurred. Necessary “dubbing out” will be charged at £38.00 + V.A.T. per square metre for each additional 15mm thickness or part thereof.

Wall / Floor Joints

[redacted] are to:

Form a Vapour Barrier Up-stand ‘Raglet Joint’ to treatment wall / floor joints as follows: -

Prepare the surface by removing any plaster remains and wooden plugs, pointing up any large holes or voids from below the line of the DPC.

Where the original plaster extends below the floor slab, this will be raked out, cleaned and the void filled to floor level. A vapour proof slurry coating will then be applied to the wall-floor intersection up to the DPC installation level. This jointing technique will considerably reduce moisture vapour condensing on both the underside of plasterwork and the rear surfaces of skirting boards, extending their life span.

Rear Wall only -

Supply and fix a slimline mesh covered membrane to the exposed wall/brickwork using sealed plastic plugs and waterproof tape to the joints

Dot and dab fix new moisture resistant plaster boards to the same treatment areas and skim finish

Refit skirting boards and pipe boxings

After re-plastering, hairline cracking of the setting coat may occur. This will not present a problem regarding the efficiency of the new plaster and should be made good when decorating.

Note - The waterproof membrane will prevent any salts or dampness from permeating to the surface of the finished plaster during the drying out period

Skirtings

Where internal DPC, re-plastering, wall/floor joints or waterproofing works have been specified, it will be necessary for existing skirtings to be removed and subsequently replaced after the works have been undertaken.

[redacted] are to:

Remove existing skirting boards as required to undertake the treatment works, and re-fix upon completion.

The internal surfaces and bottom edge will receive a liberal coating of [redacted] timber water repellent prior to fixing, to extend the life span of the timber.

Where existing plaster is being retained, it is important that it does not continue below the line of the DPC or is in contact with any solid floor (see ‘Important Notes - Bridging’). [redacted] will ensure that any offending plaster is removed to those wall surfaces where we remove skirting boards necessary to undertake our treatment works only. You should ensure that the DPC is not bridged on any remaining wall surfaces. In the event of damage during removal of these fixed items or if they are found to be decayed and unsuitable for replacement [redacted], at your request, will supply and fix new boards at an additional cost. [redacted] cannot accept responsibility for any damage caused by the removal of such fixed items."

"Guarantee

Upon completion of the contract our 20 Year Guarantee will be issued, protecting you against the recurrence of dampness rising through our dampproof course, offering you peace of mind for your property in the future. A specimen guarantee is available or can be viewed at www.[redacted].com. Whilst any general building and ancillary works undertaken by [redacted] are excluded from any treatment guarantees issued, you will of course be protected by your statutory rights under The Consumer Protection Act 2015."

 

[Deluks]

Why do they need to install a water repellent to the skirting boards if their cure-it-all chemical dpc will solve the damp problem?

 

[Deluks]

Has any remedial work been done at all since you last asked about this topic (18 months ago)
Roof, gutter, dpc, the ground level and debris?

 

[endecotp]

The inside floor seems to be at the same level as the ground outside. Often this is because the outside ground level has been raised and the original damp proof course has been buried; the fix in that case is to restore the original outside ground level. But in this case apparently the structure is only 15 years old and it doesn't look as if the outside has been changed in that period - so what has happened? Was the extension built without a damp proof course? Perhaps the client insisted that there be no internal step into the extension. This all needs to be understood.

If there is no damp proof course, or if it is below ground level and so does nothing, then their proposal has some merit. Inserting a damp proof course at a suitable level relative to the ground outside, and the doing ...something?... so that the dampness below that level doesn't get into the bottom of the wall and floor, could work in theory. But in practice these chemical treatments are ... controversial, maybe?

All the previous comments remain valid (read them all again!). Knocking it down and rebuilding it properly should not be ruled out.