Ask Jeff? B@ll@x

dampdaveski

sorry wallbash. I was guilty of generalising there,(as a lot of people do on this forum) though to be fair I didn't know you was a builder.
I stand corrected and the first thing to do is most definately checking for all the other problems you mentioned

wallbash

Now you really have p***ed me off :rotfl:

Wallbash is never /ever a professional builder
I class myself as an enthusiastic diy'er ( playing for nearly 40 years)

dampdaveski

There's just no pleasing some people
you should be a builder, you have the right temperament for it, muwahaha
fondest regards
DD

ormus

its a toss up whos worse, double glazing salesmen or the damp proofers?
it takes some doing to have a worse reputation then a DG salesman.

melb

sorry hope you don't mind but I have a damp/condensation problem we just can't shift. It's on a chimney breast of an 1890's house - outside wall - solid brick construction wall and goes about half way down and up onto ceiling. It shows itself in browny patches and is worse after rain. We have tried various different types of cowls on the chimney - we have had the outside wall repointed in places we have been up into the attic above and there are salt deposits on the floor but nothing excessive we have now taken off the plaster and replastered and yet the problem persists. We have redecorated (about a year after plaster was replaced) and the staining is back probably worse than ever. any thoughts/advice please?

dampdaveski

melb,
if you can discount water coming down the chimney, then it sounds like sulphate contamination of your plaster. when you relpastered the area did you use a gypsum based plaster such as browning or bonding? if so this is the reason why it's come back wioth a vengance. you need to replaster using a sand cement render incorp a waterproofer OR apply a cavity mesh membrane system and plaster on top.
Ormus
I agree it's a difficult to determine BUT don't tar everyone with the same brush,

hope this helps

mikey72

dampdaveski wrote: »

Hi All,
thanks for the compliment canuck
Just to add my bit
1. Rising damp does exist
2. BS6576:2005 (thats the British Standard ) tells us how to treat rising damp, who writes it - the BRE
3. Uncle Jeff tells us rising damp doesn't exist, bit controversial? He invites you to buy his book to find out more -.-!!! (yes I'm paraphrasing a bit here)
4. The damproofing industry has an awful reputation, most of it well deserved
5. This damproofing surveyor DOES NOT go out to sell damp proof courses, I go out to sell a solution, even if it's just free advice
6. 'get a builder in' what's he going to do? my experience is that he will tell you it's rising damp because he's ignorant, buy the gear off a web shop and rip you off, probably not intentionally but there you have it
7. ormus, it takes years and years for true rising damp to affect a property, as for the BRE refer to point 2
8.The telegraph, I won't buy it as there isn't enough pictures in it ;o) , maybe Jeff has lots of pictures in his book!
9. Rising Damp does not smell
10. If there is mould on the wall it is extremely likely that rising damp is NOT the cause, mould is effectively a plant, salt water kills plants, rising damp is from the ground, therefore it is salt water(chlorides and nitrates principally)
11. if anyone tells you mould IS due to rising damp they are either stupid or attempting to defraud you
12. Rant over, don't know about you but I feel a lot better )

All the plants in my garden grow in the ground, apart from the ones in the brick and concrete planters and raised beds, and if they are lucky get a nitrate fertiliser as well.

David_Aldred

Hi all - chimney breast issues first floor - none of it rocket science and all of the above along the right track. Chimney breasts are great when they are used for what they are designed for - that being having a roaring coal / wood fire in constant use within them giving lots of air changes to rooms and keeping the hearth / chimney breast / stack considerably drier than when that ceases and they often form a moisture resevoir. Things to think about - is moisture coming down the stack, is condensate within the stack / chimney breast an issue and are sulphates and other contaminates from the soot lined flue migrating into the plaster including your recent replacement plaster. Rule out moisture coming down the flue which you have tended to by fitting a cowling (which should be under the guidance and written approval of a Gas Safe - formerly CORGI plumber if appliances / fires still serve the flues) and check the flaunching (mortar securing the chimney pot) is not cracked. Look at moisture coming down the stack brickwork itself - If it is a hip roof there may be little amount of chimney breast brickwork actually within the roof void space and if there is no damp proof course (and I do not mean lead flashings around the stack here but a true damp proof course often in lead ) through the entire depth of the chimney stack brickwork just above roof level there is nothing to prevent the moisture within the chimney stack brickwork above roof level migrating down into areas below which can be considerable with a tall stack. Check there is no debris between the ceiling rafters and chimney breast brickwork in the roof void directly above which would act as a moisture resevoir. Investigate condensation by dew point anlaysis if possible and be mindful of warm moist air entering redundant flues and condesing out if the dew point is reached. Contaminated plaster will not recover and if not to an appropriate spec including substrate preperation will fail to hold back contaminates. Don't forget plaster contaminated by some salts will attract moisture to its surface from the room itself. Substrate prep and re-plastering to an appropriate spec is often required or as indicated by others an alternative is to to fit a waterproof membrane with appropriate vapour barriers and dry line using foil backed boards avoiding hygroscopic plasterboard adhesive in favour of a mechanical fix or adhesive suitable for damp situations. The ceiling plaster can be masked with stain blocker to some extent but often this is unsatisfactory and new foil backed boards isolated from the breast are required. Ensure there is no condensation issues within the roof void. One of the problems for a layperson is knowing if a plasterer is working to the correct spec and they generaly will want paying whilst the plaster is still damp / attempting to dry out and hence seeing a membrane lining as a physical barrier sometimes gives a client more confidence than hoping the plasterer worked to such an appropriate spec. Remember the rate of drying down is slow and the best that can be hoped for is 25mm masonry thickness per calender month once the moisture source (if not simply contaminated plaster) is resolved. Hope this general advice helps - Kindest regards David Aldred

melb

david aldred and dampdaveski thank you very much for your replies - I shall read through them in detail later and try and remember exactly how the plastering was done.

melb

Thankyou so much!!