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- Rising Damp - Your Questions Answered
- Woodworm, Dry Rot and Wet Rot - Your Questions Answered
- Cellar waterproofing and Tanking - Your Questions Answered
- General building preservation - Your Questions Answered
- Wall ties - Your Questions Answered
- Condensation
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HOW MUCH DOES IT COST TO TREAT RISING DAMP?
Question:
HOW MUCH DOES IT COST TO TREAT RISING DAMP?
Submitted by: PGA
Answer:
A question we are frequently is asked is ‘How much does it cost’ to carry out different types of remedial treatment in a property. Experience shows us that there are regional variations but we also know that there are sometimes enormous differences between companies quoting for the same work. It is important in these circumstances to very carefully compare who is quoting for what and who is omitting some aspects of the work that others may be including. If you go to the download section of our site and download our free PGA Manual 2 ‘Getting on with the job’ it contains some very useful guidance:Larger organisations obviously have greater overheads than a sole trader and logically one would think this should influence prices but it is not always the case. So what is a reasonable price?
The price a contractor charges is usually made up of two elements: 1) The labour charge which normally includes all overheads etc. and 2) costs specific to the job such as materials, plant hire, rubbish clearance etc. Outlined below are three different trading styles for three different types of contractor:
1. The organised sole trader
Let us look at a sole trader who rents a small yard employing a labourer and his wife on a part time basis. He wants to earn £30K per annum, his labourer £17K and his wife £10K. If we now factor in all overhead costs associated with running such a business over a twelve month period a figure in the region of £85K would need to be generated for this type of business just to stand still.
If we now deduct holidays, bank holidays, illness provision etc this leaves our organised sole trader 44 working weeks to generate £85K. Divide £85K by 44 weeks and he needs to earn £1931 per week. Divide this number by 5 and he needs to earn £386 per day. It is important to remember however that this is just the ‘labour only’ element of the job. The cost of materials, rubbish clearance, plant hire etc. specific to the job would be in addition to this figure.
2. The less organised sole trader
If we now look at a contractor who works on his own form home with no yard, wanting to earn £25K per annum, cutting back on certain overheads and targeting to work 46 weeks in a year. He would need to generate somewhere in the region of £35K per annum in labour costs to achieve this. On this basis a day rate of £152 would be necessary plus materials.
3. The small organised company with four vans
Finally if we now look at a small organised company with a director/surveyor, one other surveyor, 2 office staff, five operatives and four vans. This company would need to generate £365K per annum in labour costs. However because the company has four working vans the day rate requirement would be somewhere in the region of £400 – surprisingly not too dissimilar to the organised sole trader in 1 above.
Timber preservatives and rising damp treatment fluids and creams are relatively speaking not very expensive. Cellar conversion work using membranes, sumps and pumps does have higher material cost content. To gain an approximate idea of how much a job might cost therefore depends how many man/van days the job will take plus materials. There is no industry set price per meter run of wall or square meter of surface to be treated.
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A COMPANY WANTS TO DELAY REPLASTERING
I will be having a DPC carried out on a new home I am purchasing. The company quoting for the job is well established and members of the BWPDA. I do believe the quote is overpriced. They say they must re-plaster immediately with "THEIR" specified plastering system immediately after DPC. However another Company quotes from the Dept of Environment leaflet 58 recommending that replastering be delayed as long as possible to allow soluble salts to move from the brickwork. If I can wait that would be preferable. What do you think?
Question:
A COMPANY WANTS TO DELAY REPLASTERING
I will be having a DPC carried out on a new home I am purchasing. The company quoting for the job is well established and members of the BWPDA. I do believe the quote is overpriced. They say they must re-plaster immediately with "THEIR" specified plastering system immediately after DPC. However another Company quotes from the Dept of Environment leaflet 58 recommending that replastering be delayed as long as possible to allow soluble salts to move from the brickwork. If I can wait that would be preferable. What do you think?
Submitted by: Vartan
Answer:
We are very familiar with the thinking behind delaying re-plastering.
It takes many years for the concentration of hygroscopic salts deposited in wall plaster as a result of rising damp to build up to a level that they cause a detrimental problem to wall finishes. Therefore it is likely that the greater amount of salt migration into the existing plaster has already happened and any that will occur following the injection of a remedial DPC will be small and for this to happen will take a considerable time.
The leaflet that you mention is not familiar to us and we believe it may be an old BRE leaflet. A correctly formulated sand and cement render incorporating a waterproof additive in the gauging water is a chemical cure and more than capable of preventing the migration of salt and residual moisture to the new decorative surface. In our opinion it is not necessary to delay re-plastering. We are aware that some companies use the delay tactic as a ploy to 'cherry pick' the profitable element of the work i.e. the drilling and injection. They will then come back twelve months later and quote a huge price to re-plaster so be careful.
There is no reason to delay - so have it all carried out at once which will enable you to live normally more quickly rather than wait a year in limbo for no real gain. Make certain the same company carries out the DPC and replastering to avoid split responsibility and you should get about three quotes.
Good luck and let us know how you get on.
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SHOULD I DELAY REPLASTERING?
I am will be having DPC carried out on a new home I am purchasing. The company quoting for the job is well established and members of the BWPDA. I do believe the quote is overpriced. They say they must re-plaster immediately with "THEIR” specified plastering system immediately after DPC. However another Company quotes from the Dept of Environment leaflet 58 recommending that replastering be delayed as long as possible to allow soluble salts to move from the brickwork. If I can wait that would be preferable. What do you think?
Question:
SHOULD I DELAY REPLASTERING?
I am will be having DPC carried out on a new home I am purchasing. The company quoting for the job is well established and members of the BWPDA. I do believe the quote is overpriced. They say they must re-plaster immediately with "THEIR” specified plastering system immediately after DPC. However another Company quotes from the Dept of Environment leaflet 58 recommending that replastering be delayed as long as possible to allow soluble salts to move from the brickwork. If I can wait that would be preferable. What do you think?
Submitted by: Vartan
Answer:
We are very familiar with the thinking and some of the reason behind delaying re-plastering.
It takes many years for the concentration of hygroscopic salts deposited in wall plaster as a result of rising damp to build up to a level that they cause a detrimental problem to wall finishes. Therefore the amount of ‘additional’ salt migration into wall plaster that will occur following the injection of a remedial DPC will be small and will take a considerable time to happen.
The leaflet that you mention is not familiar to us and may be an old BRE leaflet. A correctly formulated sand and cement render incorporating a waterproof additive in the gauging water is a chemical cure and more than capable of preventing the migration of salt and residual moisture to the new decorative surface. In our opinion it is not necessary to delay re-plastering. We are aware that some companies use the delay tactic as a ploy to 'cherry pick' the profitable element of the work i.e. the drilling and injection. They will then come back twelve months later and quote a huge price to re-plaster so be careful.
There is no reason to delay - so have it all carried out at once which will enable you to live normally more quickly rather than wait a year in limbo for no real gain. Make certain the same company carries out the DPC and replastering to avoid split responsibility and you should get about three quotes.
Good luck and let us know how you get on.
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SHOULD A BUILDER DO THE REPLASTERING?
A company has given me an estimate to install a new damp course but wants my builder to do the re-plastering. What do you advise? Question:
SHOULD A BUILDER DO THE REPLASTERING?
A company has given me an estimate to install a new damp course but wants my builder to do the re-plastering. What do you advise? Submitted by: W. Roper
Answer:
We would always advise that who ever installs the new damp proof course should also be responsible for the re-plastering. The control of rising damp is two distinct processes; 1) the installation of the new damp course and 2) correct re-plastering necessitated as a result of the rising damp. These two processes should always be undertaken by the same company.
If the re-plastering is carried out by others and a problem arises in the future then the potential exists for the damp proofing company to blame the plastering and the plasterer to blame the damp proofing company with you caught in the middle! To avoid a ‘split responsibility’ situation ever happening always have the DPC and re-plastering carried out by the same company.Companies that want others to do the replastering are 'cherry picking' the easiest and most profitable part of the job which is the drilling and injection process and they should be avoided. If your company will not do both - get someone else.
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DOES SEWAGE AFFECT A CHEMICAL DPC?
Please can you confirm raw sewage will affect a chemically injected damp proof course together with surface water flooding of a lower ground floor dwelling that will require sterilisation and re-injection of a new chemical damp proof course together with newly tanked rendered plastered walls?
Question:
DOES SEWAGE AFFECT A CHEMICAL DPC?
Please can you confirm raw sewage will affect a chemically injected damp proof course together with surface water flooding of a lower ground floor dwelling that will require sterilisation and re-injection of a new chemical damp proof course together with newly tanked rendered plastered walls?
Submitted by: Peter R
Answer:
A correctly installed chemical damp proof course is chemically bound to the masonry into which it has been injected. No flood or raw sewage will reverse this process, remove it, dilute it or wash it away. It is therefore difficult to justify further injection in these circumstances though we are aware many seem to take the opportunity and reinject but in our opinion it is not justified. On what grounds is it being argued that reinjection is necessary? What is the chemistry being applied?
We agree that wall plaster will be contaminated and will have to be renewed and care should be taken that the replastering complies with the specification stipulated by those responsible for the initial injection. It may also be wise to formally inform the company responsible for the initial injection that a flood has taken place and wall plaster is being renewed to their specification - just in case there is a claim situation in the future and they argue that a major event occurred and they were not notified.
Would be interested to hear how this progresses.
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IS IT ESSENTIAL TO RE-PLASTER?
Is it always absolutely necessary to re-plaster if the original plaster is in good condition (following chemical injection). I do understand that hygroscopic salts can contaminate the plaster but does that always occur? Are there any other tasks you can consider, i.e. using a dehumidifier for a period before deciding whether or not to re-plaster?
Question:
IS IT ESSENTIAL TO RE-PLASTER?
Is it always absolutely necessary to re-plaster if the original plaster is in good condition (following chemical injection). I do understand that hygroscopic salts can contaminate the plaster but does that always occur? Are there any other tasks you can consider, i.e. using a dehumidifier for a period before deciding whether or not to re-plaster?
Submitted by: CW
Answer:
A remedial chemical damp course system is a two part process. One part is the injection and the second part is correct re-plastering. There is no way around this. If a wall has been diagnosed with rising damp then the wall plaster will have chlorides and nitrates present regardless of how sound and firm the wall plaster is. No amount of dehumidification, fans, heat etc will remove or dilute salt contamination. Bite the bullet and renew the plaster to the correct specification otherwise problems will occur in the future especially when you try to sell.
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SALTS COMING THROUGH NEW PLASTER
I have recently had a damp course done on my 200 year old cottage, and as instructed taken everything off back to the stone 1 metre high. This has been replaced by sand and cement then skimmed over the top. The problem I am having is what seems to be patches of salt coming through on the sides of the reveals which cannot be painted over as it just bubbles the paint and flakes it off then just rebuilds the salt layer. The new walls have been up one year now and the problem seems to have got worse with the cold weather. How can I cure this problem?
Question:
SALTS COMING THROUGH NEW PLASTER
I have recently had a damp course done on my 200 year old cottage, and as instructed taken everything off back to the stone 1 metre high. This has been replaced by sand and cement then skimmed over the top. The problem I am having is what seems to be patches of salt coming through on the sides of the reveals which cannot be painted over as it just bubbles the paint and flakes it off then just rebuilds the salt layer. The new walls have been up one year now and the problem seems to have got worse with the cold weather. How can I cure this problem?
Submitted by: Mark
Answer:
The salts that you see forming are almost certainly sulphates. However the fact that they continue to form are an indication that moisture is evaporating from the point where they form. A common reason for this is a 'weak spot' in the underlying render as it is failing to contain residual moisture still in the wall. It could be 1) a weak mix 2) near to an angle and the angle beads have been fixed with carlite bonding before the render was applied or 3) an underlying slightly proud stone and insufficient render covering it. Whatever the cause the cure will be to remove the affected plaster back to the stone and re-render correctly using the correct sand/cement ratios. There is nothing that you would be able to apply onto the surface as the salts would push it off. Who did the plastering after the DPC? Have you had the damp proofing company back for their opinion? - If not you should.
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DOES RISING DAMP EVER DRY OUT?
Does rising damp ever dry out by itself or will the area be permanently damp until treated?
Question:
DOES RISING DAMP EVER DRY OUT?
Does rising damp ever dry out by itself or will the area be permanently damp until treated?
Submitted by: Emma
Answer:
Rising damp will eventually dry out provided the source of moisture has been prevented. However one of the consequences of rising damp which originated from the ground is hygroscopic (moisture attracting) salt contamination. This means that even if the source of moisture has been prevented the wall may still remain damp due to the hygroscopic action of the contaminating salts, subject to the level of contamination present. If the dampness was only present for a short time and rectified, salts are unlikely be a problem and the wall should dry.
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WATER UNDER MY FLOOR
I have a terrace house with a solid floor kitchen but floor boards in the front room. I lifted the floor boards up to find about 5 inches of water under them. What could be causing this? The neighbours filled their front room with concrete so their whole house has solid floors. Could this be affecting my house?
Question:
WATER UNDER MY FLOOR
I have a terrace house with a solid floor kitchen but floor boards in the front room. I lifted the floor boards up to find about 5 inches of water under them. What could be causing this? The neighbours filled their front room with concrete so their whole house has solid floors. Could this be affecting my house?
Submitted by: John
Answer:
No idea what is causing it without seeing it. Chances are it is natural ground water but you should have the water main and drains checked just in case. Almost certainly nothing to do with next door who probably had the same problem and it will still be there in amongst the hard core of their solid floor but as it is out of sight the belief is it is cured. Water under a floor is OK provided there is plenty of ventilation.
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BEST WAY TO DRY A WALL?
What is the best way to dry an inside wall out when you have solved the damp problem out?
Question:
BEST WAY TO DRY A WALL?
What is the best way to dry an inside wall out when you have solved the damp problem out?
Submitted by: J Glover
Answer:
There is no best way other than time. If the inside was kept warmer it would help combined with some ventilation. De-humidifiers just dry the atmosphere and therefore only have a marginal effect on the wall so are not really worth it.
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