Need advice on leaking parapet wall.

[pelicanpegs]

Property Type: 90's, Detached, Cavity wall

Hi all,

I'm looking advice on my leaking parapet walls. There was penetrating damp coming in to the bedroom on one side of the house (the same side as the pictures). After drilling a hole and taking a sample of the mineral wool insulation, it was completely saturated and has since been removed all over the house. Now when it rains heavy I can literally hear the water dripping down into the cavity. The blocks on the inner leaf in the roof space are also absorbing water. I thought that this initially due to bridging of the cavity, but seems that water is still getting to them when it rains.

The copings originally had silicone between them which was almost non existent and has since been pointed. I Don't think there is a DPC under the copings but there is some lead tray which doesn't cover the entire cavity? Also the drip seems to be too close to the house on the outside and is filled. (see pics)

I have had a few roofers out to investigate. One suggested capping over the copings with something like Aluminium Caps and the other suggested redoing the lead work underneath the copings.

Need advice on the best way to address this. Is capping these a viable option? As it has been quoted cheaper to do.

I see plenty of similar threads of parapet issues on this but most seem to be either flat wall, semi or solid walls.

Thanks
Adam

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[catlad]

Well you could drape something over the top of the parapet wall, ie a piece of shed felt folded a few inches down the sides and then to hold the felt, place a baton on either side and clamp in position and if it clears up you know its the coppings that are letting the water in.

 

[pelicanpegs]

Thanks for the tip, I will hopefully get trying that this weekend. Assuming it is the coping stones, would it be worth removing them along with the lead. Then replacing with slate to close off the brickwork and run some DPC along with new coping stones on top? Or would I be best capping over?

Any info I have found mentions any dpc or lead should overhang each end of the parapet? Which is not the case here. Most of the copings are loose and can be lifted with ease.

 

[Nige F]

In the second picture down it looks like the lead under the coping has been lapped the wrong way !! could the water simply be getting in there?

 

[catlad]

Well spotted Nige its a possibility. In the photo that shows the bottom of the parapet wall it looks like it has a channel for the water to drain out if water were to get through the copings!
that must not be working. Looking at your pictures again there seems to be to many bits of lead for my liking if the copings are loose as you say I would remove one and see what underneath.

 

[jontop]

not sure i have ever seen such an over complicated design. think i might be able to see a can of worms opening up
I would Secure the copings and cover them.

 

[jontop]

Very good pics by the way