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How much for new Damp Proof Course.

1235712

Comments

  • Toptenor
    Toptenor Posts: 19 Forumite
    repoker24 wrote: »
    Hi All,

    Can any of you knowledgeable lads give me any pointers to what may be causing this small damp patch?

    I have a 1930s semi and about two years the downstairs cloakroom sink pipe burst/split (it was one of those flexi pipes fitted from cooper pipe to tap).

    Anyway we had to have the walls re-plastered; now two years later at the bottom only about 12 inches long and about 8 inches high the paint is peeling. I have check outside and the wall seems ok. There is an airbrick directly outside where damp is occurring on inside.

    This airbrick is only about half an inch from ground level if that. Could this cause the damp on the inside?

    Ps I am an average diyer and was thinking about putting in a telescopic plastic airbrick from Screwfix to see if this solves the problem. Any feedback I would be grateful.

    Thanks

    This sounds as though the ground level is too high.
    The damp proof course is usually in line with the bottom of the air brick. If that is the case then I wood dig a trench say about 200 wide by 150 deep. The ground level should be 2 courses below the damp proof course.
    You can try to identify the DPC, usually seen from inside, under the floor. It will be a black bitumous line running horizontally along the mortar course. I would lower the ground level in any case.
  • Can anyone help? I have a 1900's 3 floor, 3 bedroom house. When I moved in it had a yorkshire stone fireplace along the chimney breast and in the alcoves on each side. Because of a damp smell I had it all removed to let air circulate which did work. Unfortunately I do get dark patches in the corners of the alcove at the bottom. When I paint the walls in the alcove they always bubble a while after. And on one side of a alcove its as if someone has stuck a handful of grit on to my wall (this is an internal wall) I have sanded this down and repainted it. I also have damp on my chimney breast. Now is this condensation? Or am I looking at a damp problem. When I had a new carpet down the bloke did say my ashfelt is all damaged is this the problem or part of it. Any suggestions would be a great help.
  • Toptenor
    Toptenor Posts: 19 Forumite
    salar01 wrote: »
    Can anyone help? I have a 1900's 3 floor, 3 bedroom house. When I moved in it had a yorkshire stone fireplace along the chimney breast and in the alcoves on each side. Because of a damp smell I had it all removed to let air circulate which did work. Unfortunately I do get dark patches in the corners of the alcove at the bottom. When I paint the walls in the alcove they always bubble a while after. And on one side of a alcove its as if someone has stuck a handful of grit on to my wall (this is an internal wall) I have sanded this down and repainted it. I also have damp on my chimney breast. Now is this condensation? Or am I looking at a damp problem. When I had a new carpet down the bloke did say my ashfelt is all damaged is this the problem or part of it. Any suggestions would be a great help.

    Am I reading correctly. Why was the carpet fitter up on your roof?
    When you talk about ashfelt are you referring to the covering on your roof . Is this an extension.
    Is the fireplace sealed off? Is a vent fitted? Is the chimney open to the elements, or is it used as a flue? From your text I take your chimney breast is on an internal wall. If its on an outside wall being open at the bottom or an air brick fitted can be counter productive as warm moist air from within the house moves up the chimney condensation can take place on the cold surfaces within the chimney. You are the relying on the movement of air to later dry that out when the temperature of the brickwork within the chimney rises above the dew point of the room air moving up it.
  • Toptenor wrote: »
    Am I reading correctly. Why was the carpet fitter up on your roof?
    When you talk about ashfelt are you referring to the covering on your roof . Is this an extension.
    Is the fireplace sealed off? Is a vent fitted? Is the chimney open to the elements, or is it used as a flue? From your text I take your chimney breast is on an internal wall. If its on an outside wall being open at the bottom or an air brick fitted can be counter productive as warm moist air from within the house moves up the chimney condensation can take place on the cold surfaces within the chimney. You are the relying on the movement of air to later dry that out when the temperature of the brickwork within the chimney rises above the dew point of the room air moving up it.

    Lol...sorry it's on my floor in the livingroom and I believe Kitchen apparently it was common to put it on top of concrete to stop damp? No my fireplace is sealed off and it has a flue. The chimney is on an internal wall. Do you think all of this is condensation then? Could that be the cause of the paint bubbling over time and the grit like effect appearing on my internal? Many thanks for your help :)
  • Toptenor
    Toptenor Posts: 19 Forumite
    I think you probably mean asphalt the tarry substance as used on the roads. I have never heard of spreading this on top of concrete within a house. When a concrete floor is laid although perhaps not in 1900 a damp proof membrane would be laid beneath to stop moisture penetrating.
    If the chimney is open to the elements rain will obviously come down. This will cause damp patch on chimney breast and probably also in alcove.
    It is normal practice when blocking off a chimney to fit a vent where the fire was and a cowl, Chinese hat or other to the chimney pot.
    This allows air to travel up and dry out any moisture which may enter, but it can cause draughts. One would also need to check that the pot was properly sealed to the chimney and water was not entering from there.
    Sounds very much to me that rain is entering the chimney and causing all your problems.
    I would initially knock out a brick where the fire was and fit a plastic vent also a cowl on the chimney pot. It will take weeks if not months to dry out. The air from the lounge would normally be warm and dry so best conditions to dry out.
    Good luck.
  • I must be really weird because I have enjoyed reading this thread. I find damp problems and how to fix damp fascinating.
  • I've been following this thread with great interest. I'm in the position that we've just put an offer in on a house and we know that the word 'damp' is going to appear on the surveyor's report. I'm now very sceptical about whether a DPC would be appropriate. The house itself is from about 1930 and the owner has laid concrete right up to the wall, and you can see the dampness in the bricks up to about 18".

    This house has also been unoccupied for probably about 6 months, with no central heating on. Given that, and the fact that the concrete goes right up to the house, isn't it likely that that's the reason for the damp? So would breaking up the concrete and letting the wall dry out (maybe with a dehumidifier too) be likely to fix the problem?

    As others have suggested, I'd be quite willing to consult an independent consultant on this, but I'd like to draw on the considerable experience of those on this forum in the first instance.

    thanks
    Paul
  • 25rts
    25rts Posts: 50 Forumite
    Hi Paul
    You don't mention the type of construction ie cavity wall or solid wall, whether the walls are rendered externally or not or whether the floors are concrete or timber suspended so it is hard to give proper advice but if the existing DPC is intact excavation of a trench to at least 150mm below the original DPC ensuring adequate drainage below before backfilling with shingle may be beneficial. However even if the DPC is functioning correctly you need to be aware that the wall will still take some considerable time to dry out (rule of thumb one month for every 25mm of wall thickness) and re-plastereing may still be necessary. Joinery items / sub-floor timbers will also be at risk of decay.

    If you decide on an 'independent' as you have mentioned a list can be found at http://www.independentdampsurveyors.co.uk/
  • David_Aldred
    David_Aldred Posts: 371
    First Anniversary First Post Combo Breaker
    Forumite
    edited 20 February 2011 at 1:15AM
    Hi Paul,
    A 1930's house should have been built with a dpc under Building Regulations applicable at time of original construction. Whilst this may have cracked with any settlement of the property it is unlikely that any such minor cracking would correlate with full wall lengths of dampness or full wall lengths of high electrical damp meter readings. There are several factors that could give rise to such high readings other than dpc failure, although that is not to say dpc breakdown may not be contributory. The ideal approach would be to look at what obvious moisture sources are apparent other than dpc failure and resolve these first if practical to do so then monitor for drying down. If areas failed to dry down then further investigation of the dpc may be justified. However for the purpose of purchase negotiations it is important that you protect yourself against suffering a loss and this being the case you do not have the luxury of having time to monitor for drying down and as such you may wish to cover all bases in your purchase negotiations even those which are not actually proven to date.

    As yourself and 25rts state looking at construction, external path levels, sub floor conditions, external defects, any solid floor / wall problems and condensation are amongst many obvious things to look for. Paths should be well below dpc level and slope away from the property not towards it in order to drain surface water landing upon such paths away from the property. Although I used to suggest a gravel bed / french drain system if paths cannot be lowered / re-directed my preferred preferance these days is leaning towards a modular drain trench system such as Aco or similar between the paths and the wall fully sealed at joints with paths / wall with flexible impervious material and discharging into below ground drainage rather than the gravel / french drain system. The reason for this is the latter I found can in some cases become compromised over time especially if not well maintained resulting in the formation of a sump for rainwater from paths to collect into and thereby concentrate a moisture resevoir against house walls permeating into walls / sub floor voids but the paths are only one of several things to look at. Hope this helps, kindest regards David Aldred Independent damp & timber surveyor.
  • Thanks David and 25rts for your useful posts. The house is from 1900 and I guess probably pre-dates the use of DPC. I don't know much about the methods of construction other than 'solid victorian'. I did try posting a link to a pic but it didn't let me, being a new user of the site (2nd attempt: www DOT pjwhams.co.uk/pix/damp1.jpg )

    I think I'll definitely appoint an independent damp surveyor if our surveyor flags it up in his report (which is 99% likely...). Great to know about the ins and outs of this before committing to unnecessary work.

    Paul
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