Damp proofing required? Plz help!

[felixculpa81]

Hello!
This is my first post here, I hope some of you gentlemen can help, I am living in a nightmare house, and I really don't want to get ripped off by dishonest damp proofers, if you can offer some help it will be much appreciated =)

I've taken some pictures to try to show clearly the problem.

There are isolated patches of damp in the house, both external and internal walls:

http://s113.photobucket.com/albums/n226/felixculpa81/?action=view&current=dampcopy.jpg

The house was built in the late 30's and there IS an existing damp course, but a you can see from the image, they have put in a concrete path all around the house, which has brought the level of the DP to just 3cm off the ground! (I have read it should be at 15cm to be effective-?)

http://s113.photobucket.com/albums/n226/felixculpa81/?action=view&current=3cm.jpg

Some people have said this existing DP failed due to age as well as being too low down.

But also...
There is a gutter drain which comes out directly onto the drive, instead of a drain, and a gap along the side of the house next to it:

http://s113.photobucket.com/albums/n226/felixculpa81/?action=view&current=drain.jpg

Could it be that the water is pouring out the drain and going under the house, effectively leaving my house standing in a pool of water? Could simply moving the down-pipe be enough to solve the problem? Or do i need a new DPC as well?

(I should perhaps also point out that there is no heating in the house - if this makes a difference. And i live in rainy cold north of England!)

Any advice is really appreciated, as i do not want to pay (and also have the kitchen / bathroom apart) if it is not necessary. But now would be the best time for me if a DPC IS needed, as replastering is to be done as soon as possible, and the kitchen/bathroom are currently quite old.

It's a nightmare living here at the moment.
Thanks in advance.

 

[felixculpa81]

Thanks, that was an accident, i thought the 'stop' on the browser had worked prior the the post being uploaded (because i wanted to add the word "pictures" to the title. Obviously not.

 

[captain_scarlet]

drainpipe is almost certainly causing a problem. move it so it can drain into a gully ( think thats what its called). lift the floor boards and have a look underneath. you should see damp or wet areas that are worse than others so would give a clue as to where your damp is coming from, ie failed /bridged dampproof course. water from that drainpipe may well be seen. check that your airbricks are clear if you have some. if you don't then get some as a priority. possibly other causes of water penetration are sewer/soil pipes, leaking water supply pipes etc. you have to be a bit of a detective or pay to have a 'specialist' fnar fnar to look things over. these i know because i've suffered them all in my own flat i bought. yes the dpc is too low, not sure whats the best way to go though? dig up the concrete or a new dpc? see what anybody else comes up with.

 

[JerryM]

Until plastic DPC was introduced into building (no date but not long ago) all houses suffered from damp. Technically called rising damp (can only occur upto ~1m up the wall). There is also penetrating and condensation.

Your pics are good and from them I am sure it’s rising damp. The most important thing in diagnosing is to visit the site as there can be other causes which could mislead ie your drainpipe.

The existing damp course that you speak of what ever it’s made of ie slate or engineering brick is no good only plastic DPC solves the problem.

The concrete path is an issue if it does not fall away from the walls. Given it’s concrete and having laid concrete myself it’s near impossible to get a fall. Not sure off hand what it should be but of the order of 25mm in 1 meter would be a typ min. Getting rid of the concrete is hard work. You would need a large electric kango hammer from a hire shop, a strong back, wheelbarrow, skip, a couple of days and any friends you can muster.

I am not convinced however you need to replace the concrete. If you did decide, i would go for gravel or 600x600 flags (easy to lay).

Moving back onto the damp. The 150mm is important. It the minimum the dpc needs to be above ground level. The other secondary problem is that the dpc inside and outside should ideally be at the same level. I think you will find this difficult to achieve given the concrete ht. I think this leads to a single solution.

But 1st the options that I know of:
1) drill into the brick and inject fluid on all external and internal walls
2) as 1 but drill into mortar and inject cream
3) tank the internal walls

I have only done 1 & 3. I believe the materials for 2 are more expensive than 1 but quicker to do so cost is probably similar. The performance is similar.

You have a party wall and you would need to get neighbours consent to carry out 1 or 2. A lot of people make it more difficult than it needs to be. It also depends on how well you get on with them and how you approach them. If you're upfront and considerate you should have no issues with the neighbours.

Problem is that damp proofing what is effectively theirs and your wall could result in damage to their plaster.

For this reason and that to make the dpc's level your internal dpc would be higher than ideal (due to the 150 above for the outside dpc), I would suggest considering tanking depending on how the quotes work out. The materials are more expensive but much quicker to do. It basically involves painting the internal brickwork once the plaster has been removed. Downsides are that 1.5m of plaster needs removing (c/w 1.0m for 1 & 2). Any electrical boxes need to be installed after the tanking and the fixing to protect against breaching the tanking. Any wood below 1.0m ie windows would probably also need dpc adding in unless uPVC (this may rule tanking out).

Regarding the potential pool of water. I have sorted this before and can advise if needed. Check under you floor boards if you’re that keen. The water in itself is not a problem except if it is causing a smell. What would be a problem is your joists if the ventilation is not good enough and water is present for long periods. Wood will suck up the moister very quickly and only needs to get to 20% saturated before it starts to rot.

This is where it gets a bit more difficult. I would recommend putting plastic dpc under the ends of the joists where they rest in the wall. The problem is access. Some houses have enough ht under the floor boards to get in and use, say a car bottle jack to lift the joists. If not then there is no alternative but to take up the floor boards adjacent the walls – big job. The only alternative is to keep the water out and enough ventilation. Again I can give a few thoughts on this if you need.

In terms of tradesmen and price. It’s very difficult. The work would involve:

1) Knocking off the existing plaster – this you could do yourself
2) Doing the damp proofing
3) Rendering (application of waterproofed mortar)
4) Re plastering – this you could get separate quotes
5) Timber treatment of the joists (dpc underneath or drilling dpc below)

All damp proofers get their materials from a chemical supplier. You could check who they are, ask who their agent is and contact him. Would suggest you get a least 3 quotes possibly with/without 1 & 4. Find out who backs the guarantee and make sure it’s a reputable company. A lot are backed by the damp proof company and if they go out of business then all is lost.

Isolation of damp is an important issue. Ask them what isolations they intend to make. This is where the source of the damp cannot be blocked eg for dpc 1 & 2 vertical holes up the wall are drilled and injected, for tanking the length of tank is extended 1.5m further than normally required. Fireplaces are difficult to sort and again ask what the plan is.

I think this should give you a better idea. Any details or clarification just ask.

 

[JohnD]

...Until plastic DPC was introduced into building (no date but not long ago) all houses suffered from damp...

...The existing damp course that you speak of what ever it’s made of ie slate or engineering brick is no good only plastic DPC solves the problem...

Rubbish!

 

[captain_scarlet]

Too right rubbish. have a read through all of roughcaster's and micilin's posts. you will learn a hell of a lot from them, i can vouch for that.

 

[ModernMaterials]

i believe that your exterior driveway is too high

 

[JerryM]

yeah! sorry about that bit of rubbish when read literally. when i re read should have sounded something like, "only the introduction of plastic dpc into new builds has cured the problems of rising damp".

 

[masona]

The house was built in the late 30's and there IS an existing damp course, but a you can see from the image, they have put in a concrete path all around the house, which has brought the level of the DP to just 3cm off the ground! (I have read it should be at 15cm to be effective-?)

Yes the 150mm from ground level to the dpc is very important

felixculpa81, have a good read at the link below for better understanding of damp problems

http://www.oldhouse.info/ohdamp.htm

The chemical damp treatments is unworkable and waste of money

 

[JohnD]

A double-slate DPC is totally impervious and damp proof and is still working well in many houses 100 years old and more. However if the wall subsides or cracks it can be damaged.

Lead, copper and bitumen DPCs are also impervious.

Engineering bricks are effective but rather expensive.

Plastic DPM has the advantage of cheapness and flexibility, and is an excellent product.

 

[felixculpa81]

Thank you so much for all the replies - this is of a great help to me!

I am most definitely sorting out the down pipe as soon as i can! - The problem is finding someone to do it fast, all the builders seem fully booked up - so I think as it seems urgent - I'll find and stick a piece of pipe on the end of it for now (a bit stupid but it will direct the water away.) I am almost tempted to try to get up to the gutter and try to move it myself - is moving guttering difficult? Do you think i could manage it if i get a ladder? (sorry for more questions).

I have had 4 different quotes for work now, and they range from ripping plaster off the ENTIRE ground floor and injecting it, then right down to isolated "paint-on" damp proofing - just on certain walls (still with the plaster off first).

The builder who said he would use "paint on" stuff seemed the most honest - and he was the only one who actually looked at my gutter, and also advised damp in the bathroom could simply be condensation...

Do you think that the paint-on solution will be as effective as silicon injection? I have been trying to find out about it but most articles seem to suggest injection as a more popular method - is it more effective in your opinion?

I have not had back any prices from the quotes yet - they should be coming through the post any time soon.


Thanks once again.

 

[JohnD]

As far as I can see:

you have cavity walls

You have a downpipe which appears to be splashing water onto the wall behind it (there may also be a leak at the back of the downpipe or in the gutter above.

You have a raised concrete path which is so close to the DPC that water will bounce up onto the wall

You have paving slabs at the front which appear to bridge above the DPC

You have a gap between the concrete and the wall that water can get down

You have some damp-looking bricks in the first couple of courses above the concrete

You have isolated patches of damp just above skirting level inside.

You need to establish the cause of damp before selecting a cure. Injected or painted-on treatments are not addressing the cause.

I might be wrong, but it seems to me that the cause of the damp is:
- water-splash from faulty downpipe onto external bricks
- rain-splash from concrete too close to DPC onto external bricks
- bridged DPC and splash from paving slabs
- penetration probably from rubble inside cavity passing damp from external to internal bricks (note that it is patches)

Please carry out your own examination to see if this diagnosis is anywhere near the truth

(you can take out a single brick to look inside the cavity. If it is not rubble, it is sometimes possible for water to run down inside a cavity, when the brickwork is damaged and there is a faulty gutter or downpipe. But rubble in a cavity is extremely common)

It seems to me that you need to:

Dig up the concrete and lower the ground level beside the house. Whatever hard surface you lay down needs to slope away from the house

Fix the downpipe and guttering so that it cannot leak, drip, or splash the house wall. i would suggest a new plastic downpipe, running into a yard gulley that takes the water to a drain or a soakaway which is not adjacent to the house. It would be convenient to do this when the concrete is being dug up.

Clear rubble from the cavity (this is quite a tedious job, but if you take out one brick, just above DPC, INSIDE the house, at points that seem to be most damp, you can fish some out with your hand and by raking. As the brick removed will be behind the skirting when replaced, it will not show like a repair to the external brickwork.

I would suggest you start with the downpipe and gutter, because it will be easiest. If you stand outside with an umbrella and a torch next time it rains, you will be able to see if the rainwater is splashing, dripping etc. and wetting the external brickwork.

It would be interesting to know if one of the internal damp patches coincides with that awful downpipe.

You also need some airbricks to ventilate the subfloor. Perhaps they are buried under that concrete.

p.s. working off a ladder to repair guttering is quite difficult and dangerous. Hire a platform tower, or find a gutter specialist who will be a lot faster.

p.p.s chemical treatments to try to overcome building defects are a very profitable business.

 

[JerryM]

I support JohnD's last post fully.

I've noticed there are a lot of lawyers using the site and i hope i've choose my words as they are meant to be received.

Blocked cavities are an important issue. It allows whatever dpc exists to be breached by water passing into the outer brick then through the debris in the cavity and then into the internal brick. I have not come across an old house that did not have debris in it enough to breach the dpc. Clearing it out is a slow long job. It's definitely worth taking 1 brick out as JohnD suggests to get a feel for the problem.

The other important point i missed from my earlier post (on the subject of breaching/bridging) is that an air gap must be left between the plaster and the floor on the inside walls (typ > 6mm, ideally 25mm). Plaster takes on water like no tomorrow. If your floor has any dampness then if the plaster is right down to the floor this dampness will bridge across onto the plaster. A lot of newly installed damp proofing's fail because of this.

On the subject of costs ask for a detailed breakdown of material and labour so you can compare quotes and fully understand where the money would be going. To the serious contractor this will not be a problem. The contractors should also point out JohnD’s observations on the total state of the situation ie leaking gutters etc.

 

[JerryM]

sorry missed this off my last reply.

see my earlier post (3) types of damp proofing to my knowledge.

Injection (1) i do myself and like it (the material costs are low and the man hours high so my profit is higher). I don't like using it in all circumstances (party walls, differing levels outside/inside). I also don't like to drill some houses as the bricks are not really held in the mortar as good as new "today’s" mortar and i feel the drilling is potentially not kind to the building. However in good bricks & mortar when the injection is being carried out it is clearly visible that the fluid is being absorbed by the bricks (as with everything there are caveats here a 4" brick for example must be drilled 3" so that the back of the brick is saturated by the fluid). In short i can see a saturated line forming as i pump and confident a good dpc is being formed.

I've not used (2) cream this involves drilling the mortar which is more kind to the building. I don't believe it's visible so it's more reliant on the drill spacing/depth and installer diligence. My suppliers says the cream is more expensive than fluid but quicker to do (less profit for me) and the end result is equal in terms of performance.

Paint on and i mean tanking (3) i also use and like very much. It is a cement based compound that started life in swimming pools. If you meen paint on like a paint in a tin then i've have no knowledge other than my supplier will not touch it.

I feel tanking would be ideal for your situation - party wall & difference in dpc levels inside/outside ie if the concrete is not removed. it makes your rooms effectively into a bath tub. It does have a few draw backs (caveats) which i can go into if needed. The tanking material is the most expensive of the 3 but far quicker to apply and very kind to the building. I particularly like that i know in all circumstances when i am finished the damp is sorted 100% (don’t forget there are some simple caveats which are sortable).

 

[felixculpa81]

Thanks once again for the comprehensive replies, i shall certainly be checking that the air bricks have not been obstructed in any way - and hopefully see if there is any rubble in the cavity at the same time.

Thanks so much JerryM for your descriptions of the different types of damp proofing... I am glad you have said that "paint-on" (ie non-injection) methods are still good in my circumstances, as out of all the men who have given me quotes - he certainly seemed most honest / reliable, but i was just scared it would be the wrong type of product.

I shall wait until his written details arrive - and hopefully they will specify the product to be used (if not i shall ring and get the name of it so i can look it up further.)


So far; 4 men have been over (measured, and stabbed the walls to differing degrees) but I have only had back one written quote (£600 + VAT for what is basically 10m2... seems a bit pricey? I shall have to wait for the others before deciding.)

I can post up the diagrams and details of the quote on Monday if anyone is interested in taking a look (-?) but i understand if that's too much.