Waterproofing external brick wall

accountingbod

Hi everyone

A while back when we had all that driving rain i had some water coming through where a ground floor flat roof extention meets the back of the house.
As well as checking the flashing, i have had a builder recommend that the brickwork may have been penetrated by the rain.
I don't think i have a cavity tray where the extension is which meant the water came through the ceiling! Not being made of money at the moment, I have wondered if i could 'waterproof' the brickwork myself above the extension?

I think i could but wondered if you had any suggestions for products to use as i read that you should try and use a product that still lets the brickwork breath? I'm planning on doing it tomorrow if not raining and if the cold doesn't destroy me!

Thanks

Tucker

Why not look at doing the job properly and having someone retro-fit the cavity tray and weep holes?

It's not a huge job. Sealing the brick might not be the answer anyway, as it could well be condensation that's building up inside the cavity.

accountingbod

Thanks tucker. That is a good idea, but we had our whole kitchen recently plastered and as it cost a fair bit I would be reluctant to have it torn down again! Can you fit a cavity tray from the outside wall easily?

jkpd

Have cured similar problems with thompsons waterseal,at least two coats,still allows brickwork to breath.To insert trays would be removing brickwork etc will cost £200min,try waterseal first B&q etc stock it £20ish.

Tucker

Yes, it is fitted from the outside wall.

Basically, you remove a few rows of the external brickwork above the extension in small sections, put a plastic cavity tray in and weep holes, rebuild and then move along the wall.

All future moisture in the cavity will then run into the tray, out of the weep holes and out of harms way.

I had one put in above my extension and not a big job for a brickie to do and the right fix.

panchenlama

don't use thompsons if you ever intend to paint the wall

G_M

the brickwork may have been penetrated by the rain.

Rain does not penetrate brickwork unless there is a more basic fault. Pointing failed; flashing; etc. bricks have been used to build houses for hundreds of years. If they let water in, someone would have noticed!

Cause could be internal (condensation) in which case sealing the brickwork will just make things worse.

But more likely there is a problem with the construction of the extension roof and/or how it joins the wall. That's what you eed to fix.