Damp on garage wall / floor

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Hi Guys,
I've had a look on this site but couldn't really find anything the same issue as mine.

Hoping someone can help.
I have not long moved in to a house with a detached double garage made of single skin brick.
With the recent heavy rain I have noticed damp coming in at the base of the wall.

I'm going to be using it as a garage workshop, but would like it as dry as possible.

The DPC is about 10mm above the floor level inside the garage. Outside the majority of the DPC is 2 bricks above ground level apart from one area where a flower bed is. I plan to dig down and lower this area to stop the damp coming in above the DPC to try to stop this and maybe fill with shingle to help water drain away.

The concrete floor inside the garage seems to have a DPM as I have taped a piece of clear plastic to the floor and left for a few days and there is no condensation under it. I have also used a cheap moisture meter which measured it at just under 11%.

The point I am stuck with is what to do about the DPC being above the floor level inside the garage, especially at the garage door at the front where the DPC is level with outside ground level, so you can drive a car in. Water sitting here seems to come in under the DPC.

Is there anything I can do to try and stop the water coming in at the DPC level?
Don't really fancy digging the floor up and relaying it!

Many thanks in advance.
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[oldbutnotdead]

That looks more like a water problem than a damp problem. Have you looked at the guttering when it's raining (to make sure water from the roof is actually going in it rather than over or undershooting). Do any puddles form outside the wall where that wet patch is?
And critically, does the garage floor slope slightly towards the door- if not then you'll always get a bit of wet coming under there.

 

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That looks more like a water problem than a damp problem. Have you looked at the guttering when it's raining (to make sure water from the roof is actually going in it rather than over or undershooting). Do any puddles form outside the wall where that wet patch is?
And critically, does the garage floor slope slightly towards the door- if not then you'll always get a bit of wet coming under there.

Thanks for your reply. The picture of the wet patch is at the back of the garage where on the outside the flowerbed is up to dpc level. I'm going to drop this down to try a relieve this. Gutter is all working as it should and is clear.
The damp at the front is nowhere near as bad as that.

The front area i wouldn't say i have noticed any puddles but i guess you can get a small puddle in heavy rain before it drains in to the channel drain as the drive slopes slightly to the garage door.
Yes the garage floor does slope very slightly to the door.

 

[oldbutnotdead]

Ah ok- yes drop that flowerbed & the wet patch will go away. The rest of it will be ok with reasonable ventilation (if you stack stuff you love against the wall put a bit of polythene behind the stuff first,)

 

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Ah ok- yes drop that flowerbed & the wet patch will go away. The rest of it will be ok with reasonable ventilation (if you stack stuff you love against the wall put a bit of polythene behind the stuff first,)

Thanks for the tip. I was going to have a unit there to house my car cleaning stuff. Looks like it will have to be off the floor. Is there anything i can use to seal below the dpc to the floor to stop any damp coming in under the dpc or is it a lost cause?

 

[oldbutnotdead]

There's all sort of magic gunk you can try but ventilation is the most reliable cure. SBR render might do it but I'm no expert- prefer to keep the water out in the first place

 

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There's all sort of magic gunk you can try but ventilation is the most reliable cure. SBR render might do it but I'm no expert- prefer to keep the water out in the first place

Thanks. I would prefer to try and stop it getting in but i don't see a way of doing that without digging the floor up and putting a DPM in and up in to the brick join. Just wondering if there is a easier way that is less involved.

 

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Ok so u have dug out a bit next to the back of the garage where the earth was up to DPC level. But don't know what to do about this bit of concrete below the neighbours fence which is above dpc. Anyone any suggestions? Cheers. Ads

 

[oldbutnotdead]

Ah, that's annoying, and it looks like a path rather than anything else. Do you get on with your neighbours- best bet would be to cut 100mm of that concrete out and either leave a gap or dig another 100mm of soil out and chuck some pea shingle in. Have a look at your property deeds and see if there's any sort of gap between that wall and your boundary line- if there is then you are in a far stronger position.

 

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Ah, that's annoying, and it looks like a path rather than anything else. Do you get on with your neighbours- best bet would be to cut 100mm of that concrete out and either leave a gap or dig another 100mm of soil out and chuck some pea shingle in. Have a look at your property deeds and see if there's any sort of gap between that wall and your boundary line- if there is then you are in a far stronger position.

It's a raised part whic forms their patio on the otherside of the fence. I do get on with the neighbours but have only lived here since January so don't want to rock the boat. The fence is my neighbours and their garage joins ours on the otherside of the fence.

I'm wondering could i put a piece of dpm between the concrete and wall to stop the moisture or would that not work? There is a slight gap where i could slide it in i think.

 

[oldbutnotdead]

You could give it a go...might be better with a bit of felt support tray (rigid plastic) or maybe some Flashband (that way you can maybe get it to stick to the wall). Naughty neighbours building above the dpc & butting up to yr wall

 

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You could give it a go...might be better with a bit of felt support tray (rigid plastic) or maybe some Flashband (that way you can maybe get it to stick to the wall). Naughty neighbours building above the dpc & butting up to yr wall

Thanks. Yes I agree. they shouldn't have really done it, but I guess the issue is their garden is a bit higher than ours anyway so was probably always like it. They have got pea shingle down on their side in a trench next to the garage, so it would only be the bit where the fence is that is above DPC.

I think I will try to slide something in there first and maybe dress in to the mortar join bit like when you do lead flashing on roofs. Hopefully that may prevent it. It's only a small section.
Thanks for your help.

 

[Mr Chibs]

Try a piece of DPC it's thinner, or even two three sheets of DPM anything to slide it to try.

I keep an old saw for jobs like these, where you can saw away in thin gaps to open it up a little more. Good luck.

 

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Try a piece of DPC it's thinner, or even two three sheets of DPM anything to slide it to try.

I keep an old saw for jobs like these, where you can saw away in thin gaps to open it up a little more. Good luck.

I have a couple of old saws so good tip thanks. I have some DPM already from doing a shed base so will try that first.

I'm hoping as it's such a small area and the concrete does have a fall that it may work. The main area where the damp was getting in I have dug down and will dig down a bit more before putting some breathable membrane in and filling with pea shingle to hopefully prevent that. I'll also do a bit of repointing of the bricks in that area too.

Whatever I do has got to be better than what it was like.

 

[opps]

Although not conventional. I the past I have used expanding foam to create a DPC. Eg when I built my garage, the wooden door step was way above the garden level. Before too long, the garden height was raised and water used to run under the timber step. I decided to drill a series of holes and squirt in expanding foam. 18 years later, it is still waterproof.

With regards to your neighbour's concrete. You could try drilling both horizontally and vertically and then squirt the foam in. UV light will turn the foam at the surface orange, but it won't penetrate that far down.