Curing damp ingress ...

[RogerS]

...or how Roger made a faux-pas.

Sometime back I put in a new window but now realise that I cocked up the DPM. I should have wrapped it vertically up the inside face of the stone cill. But I didn't. So water gradually accumulates between the DPM and the stone cill and then pools onto the top of the dwarf wall and we get damp coming through the plaster.

I could Synthaprufe the internal face of the dwarf wall but would rather try and stop the water coming in in the first place. But cant really see a good way forward. If the existing DPM was dry then I could try applying a load of gorilla glue onto a second piece and sliding that in between the existing DPM and the stone cill. But it isn't. Expanding foam ?

Any suggestions very welcome. TIA

 

[Soylent1]

Hi Roger,

I know it's not an ideal fix, but couldn't you just seal the external joint between dwarf wall and the stone sill with a bead of silicone etc...? you would have to replace it every so often but it should stop most of the water getting in. It sounds to me like the top of the dwarf wall is slightly sloping back towards the window as you are getting pooling against the bottom of your stone sill ?? A more permanent solution would be to cut a slit in the external face of the stone sill, slide in and seal a piece of DPC in the slit, fold it down so that it overlaps the external joint and then sits on the dwarf wall (right to the edge if possible?) and then put a mortar haunching so that it makes the top of the dwarf wall have a fall away from the window. I hope this helps/ makes sense? I'm rubbish at trying to explain stuff. I could do a little drawing if it helps?
Tony

 

[hanser]

Hi Roger

Does the stone cill have an overhang and drip groove? If it does then wind blown rain shouldn't be coming through inside, other than in the most severe rain/weather which of course we've had plenty in the last few weeks. Has the window got some SW or W face to it? I guess its a 50/50 as to whether or not the rain is coming over or under the dpm or perhaps both?

I'd start with your suggestion re adding an piece of DPM to give you your upstand. For the adhesive have a look at Toolstations Stixall http://www.toolstation.com/shop/Adhesiv ... 199/p69243 It's good product, can be used in damp conditions and you can get it in 'clear' form. I'd also be tempted to run a bead/s on the external face betwixt the cill/membrane/dwarf wall. If there's the slightest gap the wind pressure will force rain coming off the cill back past the DPM.

Good luck

 

[blackrodd]

The dpc as drawn will allow moisture and ponding by the dreaded capillary action. also check how damp the wall itself is especially if it's on the ground floor.
In the normal/usual way, the dpc would be taken as you have drawn it, and then upwards in front of the stone sill, to form a "shelf" and then along towards the inside level with the underside of the window sill and sill board board thus isolating the stone sill, and damp ingress altogether, forming a half a swastika, if you like.
When the inside is bricked or built up to the same height as both the sill undersides, that is isolated too.
you may need to gently cut or chip a small recess on the outside, just under the sill to allow a good "bite"to a bead of mastic to stop water/moisture getting blown in off the weather.
HTH Regards Rodders

 

[RogerS]

Thanks for all the suggestions.

The outside junction between stone cill and window sill is sealed.

The stone cill is angled downwards and outwards slightly so water runs off it and drips off the end.

The underneath of the stone cill closest to the dwarf wall, although not sealed is bone dry. Possibly with the wind, water is being blown into that junction. An easy fix.

Think I will get the compressed air line and blow dry the DPM as much as possible, liberally coat a new piece with something like Gorilla glue and slide it in between the stone cill and existing DPM and hope for the best. Once it's dried I think I might be able to get a spatula with a load of silicon on and smear it over the join on the other side as it were.

 

[blackrodd]

If you should find that any of the areas you are sealing are wet, damp, or likely to be, you can get a mastic from wicks that will bond AND seal in damp areas, bonding many combinations of wood, plastic, masonry etc., black tube, abt £4.00
It's helped me out in many situations that occur when the dodgy house holder expect his poor oi' builder to stop leaking roofs, flashings, felting etc, halfway through the local monsoon!
rodders

 

[RogerS]

If you should find that any of the areas you are sealing are wet, damp, or likely to be, you can get a mastic from wicks that will bond AND seal in damp areas, bonding many combinations of wood, plastic, masonry etc., black tube, abt £4.00
It's helped me out in many situations that occur when the dodgy house holder expect his poor oi' builder to stop leaking roofs, flashings, felting etc, halfway through the local monsoon!
rodders

Thanks Rodders...that sounds like a neat bit of stuff to keep on hand.