The Brew Cabin

WHILST HAVING THE FLOORING UP IN OUR DINING ROOM WE FOUND TO OUR HORROR WHEN IT RAINED THAT WATER CAME UP IN THE ROOM IN THE CORNER NEAR THE FRONT WALL. OUTSIDE THE HOUSE IS A CONCRETE DRIVE, WITH A STRIP ABOUT 1FT WIDE RUNNING THE WIDTH OF THE HOUSE AND THEN DIFFERANT CONCRETE FOR THE REST. We think surface water is being wicked down the join and emerging under the floor. Also the driveway although below the DPC is only one bricks depth.
What should we do, digging the whole lot up seems a good idea, but then what and who by? Also could a clogged up soakaway be involved? The house is 1930's with extensions.

Water hanging on the sub-floor can be caused by many different things, and without seeing the property, it simply isn't possible for me to say what the cause may be. You could be right that the water is being carried in by porous brickwork or this 'different' concrete that you mention, but I can't say one way or t'other from this side of the computer monitor.

You need a building surveyor to look at it, and then a number of simple tests can be arranged that will identify the source problem. Once that's done, a remedial plan can be prepared and costed. It might be a broken drainage pipe, or a leaking water supply pipe, and nothing to do with the driveway at all, so ther's no point throwing money at that in the hope that it will rectify the sub-floor flooding.

Maybe a local builder or drainage contractor will be able to take a 'no obligation' look for you and suggest what might be the problem, but, from experience, I'd say sourcing tests (tests to identify just where the water originates ) are what's required first and foremost.

Thanks for replying,we have actually looked at a few options ourselves,we dug a deep hole in the garden, looking for a high water table, hosed the gutters with water for ages (and seen nothing)and then pooled water on the concrete join (when it wasn't raining)which then got water under the floor a couple of hours later.I did put red tracing dye into the water but could not detect it, maybe I didn't use enough.
we actually paid a structural/civil engineer £200 to come and look at it for us, but he seemed to have less ideas than us !! I am rather loath to go back to him or anyone else, the money goes out and we are no further on.It is hard to know who to trust.
rach

is the fall on your driveway away from the house? do you have a porous border around the walls? i have had my driveway overlaid with asphalt and specified to the contractor that the water must shed away from the house,as the new layer is above the dampcourse i wanted to ensure no water lay against the walls of the house or could penetrate the surface. all seems ok,but i'm not sure if this is good practice,the new surface has no seams,so logically i dont think this should be a problem.tony whats your views on this?

thanks,john.

Firstly, in reply to Rach, I'm surpised that your engineer didn't produce a written report, but then, 200 quid isn't a lot for a full and proper investigation.

Two other options spring to mind - contact your l;oacl council, who can send out an engineer to asses whether there's any health/environmental risk from the sub-floor flooding, or try your Building society, who will have a register of approved structural engineers and will put you in touch with them.

Your attempts to identify the source of the problem are along the right track, but try using a lime-green drain tracing dye, rather than the red, as it;s much easier to spot that colour.

IF, and only if, it does turn oput to be a problem with the driveway, then it's pretty easy to find a solution, but identifying the source of the problem must be the priority at this stage.


And so to Apprentice John - if you've had a bitmac overlay and it's higher than the dpc on your property, you are asking for trouble, and, should you come to sell the property, a good surveyor will spot this immediately and you could be faced with the prospect of either dropping your asking price or forking out for remedial work.

Even if the new surfacing does fall away from the walls, there is still a damp bridge above the dpc and that is, structurally, a serious issue. Actually, I'm surprised that any surfacing company (that should be any reputable surfacing company ) agreed to lay bitmac in such a way. We would never have done it, not even with a written disclaimer from yourself, and I can't think of any local surfacing co's that would have agreed.

hi tony,it was a cost saving decision made by myself, otherwise excavating the existing surface would have added about 2 grand too the bill ! the new surface is now about 20mm above the damp course.
the only other cheap alternative was to make a border around the walls and fill this in with chips,but i felt that it would be better having tarmac right up to the walls than have water soaking down to the founds. do you think i should make this border, or keep things as they are? what can happen if the damp course is below the finished level of tarmac? i can understand if i had a chipped driveway with the damp coarse below the chips,but with tarmac i wont have the problem of water lying in below the surface ?

Have a look at the relatively new page on damp courses: that gives a few possible solutions.

If your surfacing is above dpc, then you are inviting all sorts of problems with rising damp, possibly compromising the brickwork itself. It doesn't matter that the fall is away from the wall, the dpc itself is bridged and there is an easy-way-in for damp. :(