Garage damp

[Novitiate]

Hi all, new here so apologies if I've got the wrong forum, provided too much information, etc.

I've just had my first winter/heavy rain in a property with a garage built by the previous owner. The garage has become very damp and moldy. I suspect I have a trifecta of damp - penetrating damp through the concrete blocks at the back of the garage (right hand side on plan below); penetrating damp from insufficient roof material overlap (RO5 on plan below); and rising damp from the back (no damp course that I can see, RO2 on plan below). Dimensions in plan are approximate. The 4.25m2 area at the back is foundations with what looks like sunken chipboard, open to the elements, very wet. That is about 50cm above the damp showing in picture RI5, on the inside of the garage. The top of the pink mold in picture RI5 is more or less level with the chipboard area. The garage also has numerous holes and poor joins - e.g. the window shown from the inside UI1 has an open gap which you can see from photo UO2.

My goal is to get a dry garage I can use to store things in. The big question is whether this is possible, and if so what I can do about it. Within my capacity - ripping out the plasterboard inside (it's probably shot), painting the outside wall with something like Emperor Masonry Cream, potentially replacing the roof. Definitely outside my capacity - creating a damp proof course into the hillside that the garage is on. Left hand side on the plan below is downhill, right hand side is uphill. Damp coming mostly in from the right hand side.

Key question: is it worth doing anything without getting a damp course installed here on the right hand side of the plan/uphill on the garage?

Any other advice on things to do will be gratefully appreciated.

Lots of photos in the album, for the sake of sanity I've included key ones here. Rest is in a gallery at the end.

RO1: right outside 1. Shows dark patches on right hand side outside wall of garage, those are very damp. The chipboard between the bricks is also very damp. The inside of the garage has lots of mold around this area - there was previously a lean-to here which got demolished because it was full of mold (before I moved in). The pink mold in the next photo is about as high as this chipboard.

RI5: lots of mold.

RO5: roof material overlap is minimal here and damp has come in. Stuff at top is temporary tarpaulin.

Ceiling 2: damp coming in where roof overlap looks insufficient.

View album 27961

 

[PJames22]

Hi, what a project!
I think, have a DPC is important if you this is sure that you have a rising damp problem somewhere. As I read your post, you seem to can't invest in an expensive way to treat it. Have you looked at other, less expensive solutions? It may solve your "start problem" and then let you free to solve your other damp problems. Let me know

 

[Murdochcat]

I suspect the earth around the garage going up the wall is where to start

 

[Novitiate]

Hi, what a project!
I think, have a DPC is important if you this is sure that you have a rising damp problem somewhere. As I read your post, you seem to can't invest in an expensive way to treat it. Have you looked at other, less expensive solutions? It may solve your "start problem" and then let you free to solve your other damp problems. Let me know

You don’t think tanking slurry up the inside walls would work?

 

[Ivor Windybottom]

You don’t think tanking slurry up the inside walls would work?

Zero chance.

It looks like someone's bought a couple of pallets of blocks and chucked it together. There's nothing standard about any of it. From the looks of it, I doubt it's even got any foundations.

Probably the only realistic option... knock it down and start again.

The corrugated roof may contain asbestos. Send a sample for testing, treat with the appropriate level of care when removing.

 

[PJames22]

You don’t think tanking slurry up the inside walls would work?

Honestly nope. The only thing I'm sure of is you obviously need a DPC. It doesn't involves spending thousands and thousands of pounds, have you looked for cheaper solutions?

 

[Ivor Windybottom]

Look through the photos, you have to ask if any part of that building is worth repairing. The stonework on one side is vaguely interesting, in a very rustic way, although there's a crack from the door frame to the top that suggests that there aren't any foundations. The rest of it looks like it's been slung together by someone who'd never built anything before and was making it up as they went along.

Sometimes you just have to face reality. Big hammer, start again. Keep the rubble, hire a crusher and compact it into the ground under the new floor.

 

[Novitiate]

Look through the photos, you have to ask if any part of that building is worth repairing. The stonework on one side is vaguely interesting, in a very rustic way, although there's a crack from the door frame to the top that suggests that there aren't any foundations. The rest of it looks like it's been slung together by someone who'd never built anything before and was making it up as they went along.

Sometimes you just have to face reality. Big hammer, start again. Keep the rubble, hire a crusher and compact it into the ground under the new floor.

I was concerned that this would be the response. It’s a conversion of an old wood shed done by a previous owner. Hoped it was salvageable because the level three survey we forked out for didn’t raise any issues with it beyond it being “basic”, and said it was in reasonable condition. Gutted.

Thanks for the response!

 

[Ivor Windybottom]

I'm an enthusiastic DIYer, I'm not a builder or structural engineer. I'm reasonably confident it's rubbish, but don't take the opinion of one random person on the internet as gospel.

If you're in any doubt, get someone to look at it. You may have to pay a few quid and/or be prepared to instruct them to do the demolition so it's worth their while.

One thing you could easily do in an hour would be to dig down alongside the wall in a spot or two. If it's built properly then there will be underground courses of blocks/bricks and/or a substantial depth of concrete reaching down to subsoil, with no topsoil under it. If this isn't the case then there's no point in thinking any further beyond knocking it down. You'd need to add to its weight to improve it, probably significantly. So if it's already struggling to hold itself up you'd be wasting your time and money.

 

[Ivor Windybottom]

This is the one tool I'd recommend for improving it (after the big hammer)...

https://redrhinocrushers.co.uk/products/rr-4000-series/

Usually around £300-£400 per day for hire. Saves you the time and cost of dumping plus gives you aggregates to use under whatever you replace it with. Good on-site recycling, and at least gives you some value from the old shack.

 

[Ivor Windybottom]

Hoped it was salvageable because the level three survey we forked out for didn’t raise any issues with it beyond it being “basic”, and said it was in reasonable condition. Gutted.

You may be able to claim compensation from the surveyor. In which case you may need an independent official report to confirm it's rubbish before you knock it down. Well worth looking into.