Pointing coping stones

[slippyr4]

Hi All,

My garage roof forms an abutment along one of the long side walls, and is flashed against the wall with flashband. The wall is capped with concrete coping stones. I did the roofing and flashing, I had a builder put the top 3 courses of bricks and the coping stones on. I'm not happy with the work the builder has done, I could have done it better myself - he was a bit of a cowboy and i'll never put any work his way again. This is all new by the way.

Anyway, after the torrential rain the other night, there was evidence of leaking inside the garage - wet brickwork at the top of the long wall just under where i've sheeted the roof. The wet patches are on 600mm centres and correspond exactly with the joints in the coping stones.

So i think the leak is caused by two things :- firstly i have not worked the flashband into the mortar joins on the bricks well enough (i did use primer, but i think i need to warm the flashband with a hot air gun and really ensure it's stuck down in the mortar grooves).

The second problem is obviously with the joints in the coping stones. I'm not 100% certain what's up with them:-

the mortar itself is kind of soft, you can rub it away fairly easily with your fingers. Some of the joints have cracked, although this is only a few.

What i think is most likely the problem though is that the mortar is uite messy on the underside. The coping stones have a drip groove, but the mortar joint makes no effort to preserve this and there's lots of excess mortar on the underside.

Is this a likely point of failure?

When pointing coping stones, would you normally rake a groove through the mortar to maintain the drip groove?

If i repoint the joints, should I use a stronger mix than normal so the joint is a bit harder?

thanks for any tips

slip

 

[noseall]

As soon as you mentioned 'flashband' i switched off.

And you had the audacity to call your builder a cowboy....!

 

[PrenticeBoyofDerry]

What mix, did you use to point up with?

 

[slippyr4]

Hi,

I didn't point - i think the guy used 4:1, same as he laid with. Here are some pics of it this evening, on the outside.

First, you can see the wet patch in the brickwork, all the way down to the lintel, which originates at that left-most joint in the coping stones.

This is a close up of the same joint. You can see the water running down the face of the bricks - the water has come from the joint.

Surely mortar joints in coping shouldn't leak this badly!
thanks

slip

 

[freddiemercurystwin]

Coping stones and the joints between them are cosmetic and are not designed to stop water penetration that is what the dpcs and flashings are for. If it is leaking there is a problem with the flashings etc not the copings.

Is there a full width dpc under the coping somewhere and is this linked to the roof upstand flashing? A bit like this https://environment7.uwe.ac.uk/resources/constructionsample/conweb/walls/parapet1.jpg

If not ............

 

[slippyr4]

there is not dpc. this is the top of a single skin garage wall. should the coping have been laid onto dpc?

 

[freddiemercurystwin]

Single or double brick thick wall or a cavity wall, the principle is the same there should still be a dpc.