Water Ingress - Trace and Fix

[Barney12]

OK, so yesterday it rained, oh and boy did it rain. Torrential, sideways and relentless. The South and West elevations face open moor, close to 2000ft above sea level. We really can do rain. The blockworker (who's living on-site) and comes from Nottingham said "I've never seen anything like it, we don't get rain like that at home!!!"

I wasn't on site all day as I was dying from man flu (have I mentioned that before?). 

 

So I head to site today to find damp in one corner. Now this corner was getting damp before the blockwork. But I thought "ah its just ingress into the frame, once the blockworks up that'll stop".

Hah! Famous last words.

 

Some observations:

• As best as I can tell its not coming from above. Although I guess that is possible but is tracking down the inside of the frame but you would think the hundreds of kg's of warmcell would act like a great big sponge in that scenario? The third pic below is the floor upstairs which is dry.
• It doesn't seem to originate from a door/window. But  the bottom corner of the one right of the photo is a possible culprit. I know from past experience that water often follows what seems like an illogical route. If it is then its the seal or its getting past the air tight tape (which surely means its not that airtight!).
• We have two DPC's. One at ground level installed by MBC under the sole plate and one higher up (above the first line of those common rows you can see in the picture below. The higher is tucked under the external membrane and stapled.

 

Thoughts:

• Time to add a bead of silicone between the timber cavity closer and the frame. Before the render starts?
• Another bead of silicone between the blockwork and the cavity closer?
• Get the hosepipe out and do some water testing?

 

Anyone else got any purls of wisdom?

 

[MikeSharp01]

Given the way it has tracked across the floor the small Island of damp seems to reinforce the idea of it coming from above and dripping in one spot but the remainder does not. If it is driving it could get through the block work run down the inside and under the DPC below the sole plate. What is the detail for the containment of weeps through the block work? Does it get direct out of weep holes or is it handled in some other way? 

[Declan52]

Has the cavity filled up and then the rain has no where to go execpt inside under the frame. The water is running down the frame hits the dpc you have between the block work and the frame and can't get out any of the weep vents. These could be covered over by droppings from building the blocks.

[Jeremy Harris]

Could it be that the scaffold boards are acting as a gutter and directing water at one or other of the windows/doors?  In very heavy rain I could imagine that something like a hosepipe of water might be being deflected sideways. 

 

Best check would be to dry it out, then get a hose and direct it at an area, wait for a while, and see if water seeps in.

[Barney12]

Thanks guys. The upper DPC is drained with weep vents (you can just see them in the picture). The lower DPC will drain through open perps which when backfilled will be covered with clean gravel but its only a second line of defence as the second DPC is just above.

I've been inspecting the cavities as we've gone up and they're very clean. Brick layer is pretty meticulous.

 

@JSHarris the rain would be more like "bucket full's" than a hosepipe so I think my money is still on ingress through one of the windows/doors.

 

What to folk think about the siliconing of the timber closer before rendering?

[Onoff]

2nd pic, behind the vertical scaffold pole it looks like the mortar joint stops short...

[Barney12]

1 minute ago, Onoff said:

2nd pic, behind the vertical scaffold pole it looks like the mortar joint stops short...

 

Yes. That's by design so that in the unlikely event that anything got past the upper DPC the lower one can drain.

Its below the floor level so isn't likely to be the culprit.

[Barney12]

27 minutes ago, JSHarris said:

Could it be that the scaffold boards are acting as a gutter and directing water at one or other of the windows/doors?  In very heavy rain I could imagine that something like a hosepipe of water might be being deflected sideways. 

 

Best check would be to dry it out, then get a hose and direct it at an area, wait for a while, and see if water seeps in.

 

I should add that those Internorm doors/windows better be able to withstand waterjets. The rain comes in horizontal and at force in winter (and sometimes summer!).

[PeterW]

Pour a pint of water onto the floor slowly where that joint is .... I think it's coming in the door frame and running into the corner 

[dogman]

I had a similar issue. 

it turned out to be caused by the dpc that MBC fitted as it was catching the water coming off the scaffold and instead of directing the water away from the frame it was going under the sole plate 

I folded all the DPC down into the cavity and ensured there were no folds that could direct it towards the frame. 

It solved the problem  

Did you fold the dpc down the cavity or across to the blockwork?

[Barney12]

23 minutes ago, dogman said:

I had a similar issue. 

it turned out to be caused by the dpc that MBC fitted as it was catching the water coming off the scaffold and instead of directing the water away from the frame it was going under the sole plate 

I folded all the DPC down into the cavity and ensured there were no folds that could direct it towards the frame. 

It solved the problem  

Did you fold the dpc down the cavity or across to the blockwork?

 

Folded it down so it sloped away from the frame. It was thus under the first course of blocks. 

Edited September 4, 2017 by Barney12

[Jeremy Harris]

6 hours ago, Barney12 said:

 

I should add that those Internorm doors/windows better be able to withstand waterjets. The rain comes in horizontal and at force in winter (and sometimes summer!).

 

 

They are, but the outer seals are never 100% waterproof, they work by keeping most water out, and allowing whatever seeps through to drain down and out at the base of the outside of the window, via a small drain.  If the water flow rate against the window exceeds that which it's designed for (heavy blown rain), then there's a chance that the amount of leakage through the outer seal exceeds the ability of the small drain to take it away, so water may then build up and make it's way through somewhere else within the frame, or even under the frame.

 

I still think it's worth doing a hosepipe test if you can, to eliminate or confirm that this is where the water is coming in.

 

As an aside, my car never leaks when parked outside or driven in heavy rain.  It does leak water slightly through the two front doors when it's pressure washed, though.

[ProDave]

We made the one reasonably large window on the west facing elevation a fixed pane, partly because it would be behind the kitchen sink so awkward to open if you wanted to, but also partly because this will be exposed to the prevailing weather and the horizontal rain in a winter storm.

 

A door on the same elevation suffered some water ingress where the theshold of the door was not adequately sealed to the frame of the building initially.

[Barney12]

Nothing to see here. Move along

Edited September 6, 2017 by Barney12