External wall damp treatment

[Charles Morgan]

I have a multi-level patio at the back of my basement flat with high London brick walls all round, and a number of brick walls supporting the different levels. All are painted white and needless to say, a number of damp patches are apparent.

I am busy tidying it all up and giving it a good spring clean and paint (with external masonry paint, having patched, cleaned and stabilised first). Does anyone have any recommendations for treating the damp areas with sealant or similar to stop (or delay as long as possible) the inevitable discolouring of the white paint?

Many thanks in advance.

 

[jonnyboy]

Let me speak to my contact Charles as I am an accredited applicator for their range.
A picture would really help though.

 

[Cabe]

A surface sealant like Thompson Water Seal would probably do the job, but for a truly thorough job you may need a chemical/solvent DPC installed.

Thompsons - Product Details - Thompson's Water Seal

 

[Deleted member 37751]

+1 for a picture. It would help to determine the level of damp.

 

[Charles Morgan]

This is of the side wall having put a layer of masonry paint on Sunday. It could all do with being stripped and rendered, but in the short term I just want to patch rather than spend loads. The damp is never going to be sorted as these walls have a garden behind.

 

[developer]

The damp is never going to be sorted as these walls have a garden behind.

Therein lies the problem Charles - if it were a garden wall it would have (should have) drains in the wall to allow some of the moisture out. I'm guessing you can't to that because it would mean draining onto your property?

There are tanking products for basements that you could look at - they are more substantial than products like Thompson's and can still be painted, however, a garden behind a wall isn't going to be easy to fix.

You need specialist advice, perhaps starting with a basement tanking company.

 

[Charles Morgan]

Lots of familiarity with tanking and dpc living in a basement flat of an era when they weren't necessarily installed! Despite sharing a common landlord and a common party wall, my neighbour(s) over the years has always been the model of unhelpfulness, although the Italian couple who had loud domestics on their patio were at least high entertainment value!

As my needs are cosmetic and for a relatively short period as suggested offline by a couple, I am going to go for a couple of layers of stainstop and then paint over.

Thanks all, help much appreciated.

 

[developer]

Lots of familiarity with tanking and dpc living in a basement flat of an era when they weren't necessarily installed! Despite sharing a common landlord and a common party wall, my neighbour(s) over the years has always been the model of unhelpfulness, although the Italian couple who had loud domestics on their patio were at least high entertainment value!

As my needs are cosmetic and for a relatively short period as suggested offline by a couple, I am going to go for a couple of layers of stainstop and then paint over.

Thanks all, help much appreciated.

Hello Charles,
Stainstop will block a stain left over from a cured water leak - it won't stop an ongoing damp problem.

The instructions on the stain stop tin will tell you to apply it to a dry surface.
As you say, it may provide short term relief but it's not the answer I'm afraid.

 

[Cabe]

As others have said the the problem is with the earth on the other side. In most cases the proper repair would be to dig away from the wall, the wall tanked/sealed and then weeping tile placed in the bottom of the trench to drain the water away. Possibly backfilled with shingle rather than dirt.

Sadly I don't think there is a "quick and dirty" method short of building a new wall in front of the old one.

 

[Charles Morgan]

My architect (ex W124 driver, now Honda owner, boo hiss) having run through the list of party wall consents required, the potential scope of works (along the lines of Cabe above) and the potential costs, suggested as an alternative putting a plant in front of it.

Sound man, Mr Ball!

 

[trapperjohn]

Perhaps a Cheese Plant Charles or maybe a small bookcase with storage for "Sausage Monthly" magazines.

 

[Charles Morgan]

Perhaps a Cheese Plant Charles or maybe a small bookcase with storage for "Sausage Monthly" magazines.

To get that to stand upright I'd need to tie a stilt on that plant, John.....

My sausage monthly magazines are kept in a very private place.

 

[Cabe]

Nice damp wall might suit some ivy.

 

[Piff]

Dulux do a couple of paints which may help:-
The first is an oil based masonry paint - I've used it once as it is quick drying, 15 mins if I remember correctly, I used it on the inside of a basement light shaft and it seemed to hold up quite well.
The second is "cellar paint", again designed for damp walls. Applied this in a cellar once where the cellar was assumed to be dry, In fact a previous owner had diverted rainwater into the cellar to pump to a roof tank so he could bathe in soft rain water. Had a call for help from the current owners to say that the cellar had flooded. On inspection, the water was about a metre deep! Installed a sump & pump with a float switch to resolve the problem. The cellar paint seemed unaffected by the flooding.

 

[jonnyboy]

Charles

I have a call in to my guy so hang fire till tomorrow if you can

 

[Charles Morgan]

Damn, I worked all night on it!

No hurry. I shall be repairing the wood threshold of my patio doors which has become a bit rotten in places, but a bugger to replace without replacing the doors. And no, the answer is not replacing the French doors....

Currently watching Mr Blackbird having a jumbo snail feast of many of those displaced by my tidying. Alas, I haven't seen my wrens since the terrible winter.

 

[trapperjohn]

No wrens here either Charles. We used to have around 4 in the garden.

OK all you ornathologists out there. Do wrens make a come back.

 

[jonnyboy]

Right, here is my chap's advice. None of our sealants will work as they will prevent paint sticking. What he has said is get a "trade" waterproofing agent (which needs to be water-based) from the likes of Travis Perkins or the likes. Scrape off all the loose paint and use a heat gun to warm things through/get rid of dampness in the brick face. Apply the waterproofer. The paint to use though is not a masonry paint as it will last "minutes". He suggested an oil-based paint will hold-up better to dampness for a lot longer. Go to a little decorating-type trade shop who can advise further on something oil based with a matt finish.

Good luck.

 

[Dieselman]

In fact a previous owner had diverted rainwater into the cellar to pump to a roof tank so he could bathe in soft rain water.

If I had a cellar, or built a house I would employ such a system and an even larger storage for hot water to heat the house.
The rainwater idea is sound as soft water leaves no scale, you require less soap and less than 5% of water used in a house is for drinking or cooking, the vast majority is flushed away down toilets.

 

[Piff]

If I had a cellar, or built a house I would employ such a system and an even larger storage for hot water to heat the house.
The rainwater idea is sound as soft water leaves no scale, you require less soap and less than 5% of water used in a house is for drinking or cooking, the vast majority is flushed away down toilets.

Now starting a major refurb/extension of a 1930,s property and will include a "rainwater harvesting tank". I believe building regs prevent use of the collected water being used for anything other than outside taps, toilet flushing & clothes washing machines.
Unfortunately bathing water not possible.

Currently looking at large hot water tank heated by immersion heater fed by solar pv panels to supply domestic hot water & underfloor heating. Can't currently find independant competant advice to confirm if this is possible
(Hot water tank also the be heated by air source heat pump)