Another person asking about damp

[ziggy]

Hello

I've read the sticky about damp and trawled through so many specialist damp sites I'm dizzy. Anyway, can I just run something past you.

I'm renovating a basement flat. I've had two companies around to inspect/quote. Forget the first one as I wasn't convinced about his approach. Second chap made more sense, reputable company and recommended. Basically tanking. Now I've read that companies often recommend tanking as the ''wonder cure' but I think it might be right for me.

As I said it's a basement flat. External ground level higher than flat floor on all levels. At back external ground same height as ceiling, front external ground to window level, and at gable external ground somewhere between the two. The property supposedly has rising damp, penetrating damp & condensation. I've got a plumber checking the drains to understand what goes where. The house itself has just been re-roofed, re-rendered and all new guttering. New windows with trickle vents will be installed. I understand the flat always had 'damp' but because the externals were so poor, it was probably coming in a dozen ways. Now they have been dealt with - so it's just the internal decision.

Am I right in thinking tanking is the right way to go in view of the ground levels ? i realise each property can sometimes have a mix of different solutions, but tanking, from what I've read, seems most suitable for situations where the ground level is higher than the property floor. All thoughts appreciated as this tanking will cost in the order of 16K and I can't afford to make the wrong decision.

 

[PC]

Hi Ziggy,

A bit more info would help.

What exactly are these companies going to do for £16,000.... ie what system of tanking are they proposing.

Has the basement been water proofed / tanked before?

What is the extent of internal plaster damage and decorative spoiling.

Any mould, running water, wet floors??

How long have you lived there and how long where the previous owners in occupation.

Where are you located?

PC

 

[chuckey]

A freind of mine bought a house that was split into flats the lower one was like yours. It had a closing order due to the dampness in it despite the fact it had been tanked. He had dug, at my suggestion the deepest french drain you have ever seen, about 9' deep!! it was filled with 3/4" pebbles and voila, no more damp! The underground part of the house had slates mortared on to the walls providing a vertical damp course, until it failed (1890?).
As part of the tanking they had poured concrete over the internal floors, which was left because We guessed it covered some sort of damproofing.
My brother has worked on tanked houses, installing electrical stuff, all surface mounted. Every wall plug had to be bedded in with silicone, what a job! no picture hooks either. It seems that the walls were coated with a water proof substance and then plastered over, so NOTHING must be allowed to pierce the waterproof layer, else the water would get in.
Step one, chat up your neighbours, see what they have done, and what soil levels they have. Then try to emulate them or failing that, put in french drains back and front side. Its virtually all labour with a few hundred pounds worth of pebbles. If that does not cure the damp, you will not have wasted too much when compared to £16K.
Frank

 

[Nemesis]

Me, I'd answer PC's questions. He does this for a living.

 

[ziggy]

Hi Ziggy,

A bit more info would help.

What exactly are these companies going to do for £16,000.... ie what system of tanking are they proposing.
Vandex BB75 Tanking System. Says it is a water resistent 3mm thick 'breathable' vertical application ideally suited to damproofing stone,cobb & walls of mixed construction. Vandex BB75 carries an Agreement Certificate No 90/2516/C. Direct quote.I can't remember where I heard it but I think the house is about 1850 and I think it's cobb - not 100% sure though.

Has the basement been water proofed / tanked before?
No. Somebody put in a concrete path along gable side. Gable side internally has gap then drylined stud wall. Nothing to rest of flat.

What is the extent of internal plaster damage and decorative spoiling.
Worst staining on part of drylined gable wall plus section of ceiling. Rest of gable wall is kitchen with units against wall, evidence of staining in units but they haven't been removed yet so pretty sure not good. Stain from ground to maybe 3 foot on other internal solid wall. Whole flat papered with woodchip - paper loose/coming away from front wall, the front is two seperate rooms both with windows so along whole of front obviously damp.

Any mould, running water, wet floors??
Some evidence of mould in gable room with staining mentioned above. Surveyor ( third party not connected with the quotes ) said it wasn't damp but condensation. No wet floors - have spot checked a lot but carpets still down.
Running water. This is the big one. As I said someone has left a gap between the gable wall & then put a drylined stud wall. One section of this (bathroom) has a cupboard where you can see the external wall. This area has running water on external wall - very damp/wet. I am assuming the rest of the gable wall is similar, just currently hidden.

How long have you lived there and how long where the previous owners in occupation.
Recently bought, haven't lived there - waiting for listing consent to carry out refurbishment. Previous owner did live there for period but rented it out after moving in with girlfriend - I'm guessing it's been rented out for 6+ years.

Where are you located?
Somerset
PC

Our house is the end of a terrace of three ( hence the gable ). I visited the neighbour in the basement flat next door (mid-terrace). His flat is as dry as a bone but he doesn't know what was done - it was all done before he bought it. The last house in the row, other end, doesn't have a basement.

Many Thanks.

 

[ziggy]

As part of the tanking they had poured concrete over the internal floors, which was left because We guessed it covered some sort of damproofing.
Interesting. There is a section in the flat, a very large cupboard which is basically the area under the stairs upstairs - this hasn't been touched ie is original - the floor is rough brick, this floor is lower than the rest of the flat (maybe 2-3 inches ). Good possibility the 'habitable' rest of the flat had a concrete floor laid but doubt a DPC underneath and only guessing the concrete was laid on similar brick.
My brother has worked on tanked houses, installing electrical stuff, all surface mounted. Every wall plug had to be bedded in with silicone, what a job! no picture hooks either. It seems that the walls were coated with a water proof substance and then plastered over, so NOTHING must be allowed to pierce the waterproof layer, else the water would get in.
I know this and it worries me. This alone would be a major reason not to tank if I could find an alternative effective way to damp-proof. But because of the ground levels, I thought tanking was my only option.
Step one, chat up your neighbours, see what they have done, and what soil levels they have. Then try to emulate them or failing that, put in french drains back and front side. Its virtually all labour with a few hundred pounds worth of pebbles. If that does not cure the damp, you will not have wasted too much when compared to £16K.
See my answer to PC about the neighbour - his flat is dry but work done before he bought, he doesn't know what they did. I own the garden in front so could put a french drain there, but back more difficult, it's a bit unclear who owns it, it might be the freeholder of our house or the house behind us. Basically the whole site was bought by a developer back in 1990's who split the house into flats and built a smaller house behind - the boundaries/titles are ambiguous.
Frank

Thank You

 

[Nemesis]

Possibly worth sending PC a PM... bet he won't ask sixteen grand, nothing like...

 

[ziggy]

Have done Nemesis - hope he doesn't mind