Damp proofing single skin garage walls?

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Silly Car
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Damp proofing single skin garage walls?

Post by Silly Car »

Following the recent deluge of rain, we’ve noticed a few damp spots in the garage which I suspect are occurring as a result of:
  • Rainfall between neighbouring garages (<4” gap between buildings)
  • Huge snots of mortar catching rainfall and directing it against bare 7N blocks
  • Lack of airflow between buildings to drive out damp
  • Piss poor practices of brick slingers
I’m after some potential solutions / pros/cons of the following:

Seal gap at roofline between garages, flagstone / coping stones on left hand neighbour’s roof could be removed and replaced to bridge the gap, although on right side as gap is wider at roof level due to how the garage that side has been built. A epdm or fibreglassed ‘gutter / trough’ could be fashioned to span the gap and drain water into our garden - would need consent from both neighbours

Attempt to knock mortar snots off the walls and clear debris so water doesn’t pool against the blocks - minimal access to get ‘tool’ down the gap and snots could get wedged causing damp further down wall / for neighbours as well

Apply damp proofing treatment to exterior of walls, no idea what or how due to minimal access - neighbouring walls would also likely benefit from treatment but no way of realistically ensuring total coverage

Remove blocks where damp appears, clear out snots and re-insert blocks - probably 8-10 blocks at worst in total that I can see, but problem could just shift elsewhere

Render the inside walls but wary of water building up behind render and blowing the render. This could be potentially improved by applying tanking slurry effectively sealing blocks from inside. Blocks can breathe at the moment but damp can also penetrate.

Add plastic cladding / tanking membrane on inside of garage and potentially add a channel in the floor to collect / drain the water

Run in a new block wall on inside of garage wall with cavity against existing wall, reducing overall internal width by 400mm (assuming 100mm cavity) against 7m width garage

Increasing airflow between garages isn’t really feasible as street side walls are butted up against each other

Any other ideas, pitfalls or options?
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mangocrazy
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Re: Damp proofing single skin garage walls?

Post by mangocrazy »

Is there any way to install guttering between the neighbouring garages at the highest possible point? Water can then be directed away to a convenient location. The main objective should be to ensure that rainwater is diverted safely away before it has a chance to cause problems. Everything else is just a band-aid.
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Silly Car
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Re: Damp proofing single skin garage walls?

Post by Silly Car »

mangocrazy wrote: Tue Aug 15, 2023 8:48 pm Is there any way to install guttering between the neighbouring garages at the highest possible point? Water can then be directed away to a convenient location. The main objective should be to ensure that rainwater is diverted safely away before it has a chance to cause problems. Everything else is just a band-aid.
Good shout and kind of where I was going with coping stone / gutter / trough notion. All three flat roofs pitch front to back with gutters draining in to respective gardens / drains. Damp problems exist on left and right walls. Assuming there is another dry day this year I may jump up on my roof and take a proper look to see if a form of gutter is feasible.
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Re: Damp proofing single skin garage walls?

Post by mangocrazy »

Silly Car wrote: Tue Aug 15, 2023 9:46 pm
mangocrazy wrote: Tue Aug 15, 2023 8:48 pm Is there any way to install guttering between the neighbouring garages at the highest possible point? Water can then be directed away to a convenient location. The main objective should be to ensure that rainwater is diverted safely away before it has a chance to cause problems. Everything else is just a band-aid.
Good shout and kind of where I was going with coping stone / gutter / trough notion. All three flat roofs pitch front to back with gutters draining in to respective gardens / drains. Damp problems exist on left and right walls. Assuming there is another dry day this year I may jump up on my roof and take a proper look to see if a form of gutter is feasible.
Yeah, if the water can be prevented from getting to the wall you're winning. You may find other problems, but keeping that rainwater away from the wall and soaking the ground between the walls has to be top priority. With any luck you should have a good weather window through to the weekend starting tomorrow, so good luck with the investigation.
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Re: Damp proofing single skin garage walls?

Post by Mussels »

I doubt much rain is hitting the wall directly so is it running off the side if the roof? If so would a raised edge down the side of the roof work?
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Re: Damp proofing single skin garage walls?

Post by mangocrazy »

Ironically, watching the affected area while heavy rain is falling will probably be most instructive. You should be able to see where the majority of the rainwater is going and then take the appropriate steps.
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Re: Damp proofing single skin garage walls?

Post by Silly Car »

Mussels wrote: Tue Aug 15, 2023 10:05 pm I doubt much rain is hitting the wall directly so is it running off the side if the roof? If so would a raised edge down the side of the roof work?
That’s one of the strange things, my garage roof is epdm and has the kerb edges, the left one has coping stones and the right one is fibreglass and has a kerb on the main part of the roof. I’ll see if I can climb up at the weekend to see what’s happening.