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Garage conversion. damp proofing

Discussion in 'Home and Garden' started by Apex, Jun 5, 2019.

  1. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    anyone converted their garage or know about this?

    been searching online for the options, but finding information from manufacturers more than real people so not trusting to advice given as they just want to sell their product.

    we've a fairly decent sized garage that we want to split into 2 using breezeblocks, leaving the front 2/5 as a garage, and the rear 3/5 as an office space with rear french doors for access.

    none of the walls are attached to anything, unfortunately, and it's single skinned, though the view from the outside isn't brick it's got a flat surface so had an extra layer of something on it. one wall will eventually become joining of the house once we do an extension in a couple of years.

    i've looked at tacking, insulated plasterboard etc, but find conflicting views of what I actually need to do.

    advice welcome. i can upload photos later when home
     
  2. Longbow

    Sgarrista

    Joined: Jan 15, 2004

    Posts: 9,339

    Did you get anywhere with this? I've been quoted, the guy suggested metal studwork, 50mm rockwool, double 15mm acoustic plasterboard, rubber dampening between the stud and boards, and then skim.
     
  3. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    Nope nothing yet.

    What were his costs?
     
  4. Longbow

    Sgarrista

    Joined: Jan 15, 2004

    Posts: 9,339

    2k, that's a "standard" single garage though.
     
  5. eviled

    Hitman

    Joined: Sep 25, 2016

    Posts: 683

    epoxy paint the floor
    stud walls in timber and insulate in between - you want at least 50mm PIR (50mm rockwool is not a lot) keep 20mm gap from original brick skin to prevent any themal/damp bridging
    board the walls with plaster board
    lay some rigid insulation boards on the floor and then a good thermal underlay
    insulate the ceiling/roof as best you can depending on its construction.
     
  6. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    thanks for this. would you not suggest doing anything on the current single skin brick? is tanking worth doing?
     
  7. eviled

    Hitman

    Joined: Sep 25, 2016

    Posts: 683

    tanking is only necessary if partially underground, or heavily exposed, it would be beneficial to epoxy the first couple of course of bricks with the floor though.
    A cheaper option would be to us damp proof membrane on the floor, epoxy paint is quite expensive

    If you use PIR insulation boards they come with vapour control foils on either side, so if snug in stud work and taped will be sealed.

    If you look at lots of modern houses they are single skin brick with a timber internal stud work
     
  8. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    can you give a link to the epoxy we should look at?

    The bottom 2/3 bricks are actually lower than highest point of the patio outside. one wall is 2 bricks, the other is 3 lower.

    I've had a guy round that suggested something where we drill ever 10cm along the bricks and inject them to make them bone dry and that's all that's needed. ideally wanting this to be building regs standard as it looks like it'll cost more than i had first hoped.
     
  9. Josh Peat

    Associate

    Joined: Jul 12, 2019

    Posts: 1

    We had ours done recently and used Resincoat - they do an two part epoxy garage paint
    https://www.resincoat.co.uk/en/paints/49-resincoat-hb-epoxy-garage-floor-paint.html

    It sealed the floor and did the job for us, but ours was only marginally damp to start with. We just primed it with a dpm primer and sealed with the above.
     
  10. eviled

    Hitman

    Joined: Sep 25, 2016

    Posts: 683

    I would go for the better/cheaper/easier option of laying down damp proof membrane up to a few courses higher than ground level and add an air brick of too to let moisture evaporate.

    Its a better idea to plan to allow some moisture into the space between the stud and allow it to evaporate.

    [​IMG]
     
  11. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    thanks. i assume the air brick goes higher than the membrane?
     
  12. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    Just an update with this. I'm looking to purchase some dpc injection cream to raise the dpc so that it's higher than the external ground. The stuff comes to about £70 all in. From permaguard

    Then I was planning to get a dpm to go over all the walls, however I see the example above you don't go too high up the bricks. Would you suggest that anything say 3 bricks above ground or higher doesn't require the membrane? The dpm for all the walls was about £250 with all the bits needed from permaguard. Perhaps I can reduce this down and just do the first 4/5 bricks?

    I would then stud it, put insulation (though unsure which to use) and then plaster board on top of that.

    Finally insulation the ceiling I'm unsure yet what to do as I need to see what's above the current boards in place
     
  13. Marvt74

    Capodecina

    Joined: Feb 20, 2004

    Posts: 14,243

    Location: Higher Walton

    @eviled

    Just wondering. Is it normal to scribe the battons to the brickwork? Feels like a lot of effort considering the number required.
     
  14. eviled

    Hitman

    Joined: Sep 25, 2016

    Posts: 683

    @Marvt74 that picture isn't mine, and it looks like studding around a brick column, I was just using it to illustrate the damp proof membrane on the floor coming up into the cavity

    the idea in this case is to leave a gap to allow ait to circulate and dry out rather than transmit damp through contact.

    @Fairly sure the answer is no I don't think the dpc injection will add anything as long as the membrane comes up a several course of bricks and you add a couple of ventilation bricks.
    I would use heavy membrane like https://www.fastbuildsupplies.co.uk/building-products/plastics-and-polythenes/damp-proof-membrane cheaper too
     
  15. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    from what i understand, the injection is to stop damp being able to get any higher, which the membrane wouldn't stop, the membrane would stop the transfer from the brick to the inner wall/insulation. without the injection, if a brick near the bottom gets damp, the damp can then rise higher with nothing to prevent it getting worse.
     
  16. eviled

    Hitman

    Joined: Sep 25, 2016

    Posts: 683

    rising damp is a controversial subject.

    as you will be building essentially an isolated stud wall, not in contact with the external wall and with the addition of a couple of ventilation bricks I cant see you having issues.

    The argument against DPC injection is it can drive moisture laterally, or trap it and cause it to pool
     
  17. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    2 of the walls are exposed externally, 1 is "external" but it's covered by a roof, and the other only 1 wall is internal.

    1 of the external wall has soil on it up to about 5 bricks from the floor, well above the dpc.

    The other external has patio about 3 bricks above the dpc

    Is your advice above based on internal walls only?
     
  18. eviled

    Hitman

    Joined: Sep 25, 2016

    Posts: 683

  19. Apex

    Capodecina

    Joined: Feb 12, 2006

    Posts: 10,639

    Location: Surrey

    i had 2 people do quotes, and both said the lower bricks are a tiny bit damp in one place, however they were sales men trying to sell so who knows. i guess one area might be but there was a blocked pipe outside which is now cleared so would need to double check
     
  20. Mason-

    Soldato

    Joined: Jun 18, 2010

    Posts: 5,510

    Location: Essex

    In regards to 'rising damp' or damp from capillary action. I'd suggest reading through this websites many pages on damp: https://www.heritage-house.org/damp-and-condensation/the-fraud-of-rising-damp.html

    The majority of damp is caused by condensation and poor ventilation. Any 'damp experts' or installers who do injection dpc are mostly scam artists who will probe your brickwork with those wholly inaccurate damp meters which are a measure of conductivity, not moisture levels. And will then recommend injecting those dpcs which often do much worse.

    Get air bricks, and make sure any soil/gravel outside does not block them. A membrane as suggested above will stop transmission of damp through contact too.