damp in the shed

[chunkolini]

My moron built shed has a serious damp problem.
Last year I hired a moron to build a shed. Big mistake but eventually it was finished.
I fired him brutally in the summer
I did the roof myself using a rubber roof system. Tidy but gluey work. I fitted windows and made doors.
I left it for ages roof and doorless in the slough of despond. So the floor was soaked.

The retaining wall has a clean bill of health from a mate who's a surveyor.
Walls? sound but hideous block work.
The concrete base seems sound, the shed itself is a few inches above the concrete base on another layer of concrete. and bbout six inches above street level, access via small ramp inside the outside door.

the floor?
Mr Moron decided to lay about 2" of sand and cement calling it a screed. Like hell a soft dusty mess that had loads of hollows that I had to dig out and refill.
he says he put a 'damp proof membrane; under that layer. I found a black plastic sheet under the bits I had to repair. No Idea if it is a proper DPM, looked like the stuff cheap rubble sacks are made of.
there were creases and folds in the 'membrane that caused the hollows. Tap them with a hammer and they would collapse.
Floor dried out a bit the lasr few days but is soaked again

Chunko is not impressed. No point asking the Moron back to fix things. I have buried him.
What to do?
dig up the crap top layer of floor? and relay it over a proper DPM?No idea really.
Any input appreciated.

 

[fizzy]

I am guessing the damp patches and lumpy floor would improve if you removed his body and started from scratch

 

[dave h 2]

I'm with Fizzy, it's obvious where you put him.

 

[BrokenBiker]

I'm with Fizzy, it's obvious where you put him.

If you look hard enough you can see the outline

 

[dave h 2]

It's not so hard really

 

[E T]

If you look hard enough you can see the outline

I can see his outline on the left, but there's another bigger one on the right.
Who's that then?

 

[Dapph2]

It could take several months for a well wet slab with a faulty thin wp plastic . Can you get an electric fan and a small plumbed in dehumidifier in there ? I'm betting you'll pull 20 litres of water out a day for a few month> I'd also suggest that you spray the outside & inside including the floor once it is dry .with something like Finnigan's limestone water proofer inside & out side.

Then when there is no chance of frost either render it and paint with water proof paint or spray it with a terylene dressing .
If that's too expensive pop a CLS cladding on and cover in wriggly tin as the open block work will simply act like sponge to the local liquid sunshine .

A simple check to see if the floor is really dry is to make a 10 inch ring 1/2 " wide of blue tack or similar gunge and press a glass plate on it . within a few hrs. you will notice condensation on the inside of the plate when it almost disappears the floor will be suitably dry .

For my garage about to become an office at my last house I put 2/3 of a 25 litre drum of rubberised bitumastic paint on the floor and sealed it 2 foot up the wall left it for a week then sprinkled dry cement powder over it to remove sticky ness and put down my own 50mm thick sharp sand floor screed with a water proofer in it . I lined the walls wwith tar paper as a moisture membrane slapped on a CLS stud frame filled it witht eh wiring aand insulation batts then put on feathered foil backed wall board . once coat rolled on skim and painted it
Two weeks later I put down a floating engineered wood floor then ready painted skirting boards etc..

 

[voipio]

It definitely been rather damp lately in your part of the world @chunkolini . Any simple single skinned wall is going to wick water across it. It's worth using an aqua-vac, or a large broomstick-sized squeegee to get rid of the surface water in the shed, and go in and see where the water is coming in, next time it rains. It should become fairly obvious. There could be more than one point of entry, which might only be revealed after the main source is located and fixed. Might the door to the roadway, where the white van is parked, have something to do with it? Not sure of the layout you have there.

 

[Dapph2]

To prove to the insurers that my bungalow was still wet after the problem was supposed to be cured seven months on , after having two massive Andrews For Heat Hire dehumidifiers running 24/7 the insurers sent a guy with a stupid two pronged wall paper moisture tester , who declared that at 22% iy was dry enough for us to move back in and get our moulding stuff out of storage.
So I drilled four holes in the driest part of the bungalow, some four feet apart and with my multimeter set to meg ohms showed the assessor 2 meg ohm reading over/ across all the holes .
Did the same in the bathroom where the underfloor leak had occurred and got readings of less than one meg ohm . Took a lump of concrete from the car that I had dried out in my oven over night after finishing roasting a joint of beef and it read infinity . Had to then show him what that meant on bits of wet & damp wood , that his guy hadn't a clue as to what he was taking about . The drying out paid for by the insurers continued , with me still keeping my daily extraction readings log book for each machine .

Five months later I convinced the insures assessor to let me hire a clamshell moisture metre which I stuck to the floor in the bathroom . It was agree that we stayed in our rented fully furnished accommodation till we got down to the 12 % moisture in the floor concrete which took another four months of drying out . By this time most of the ceiling boards had either dropped off the rafters / joists or had bowed so much I had to hire a collated screw gun and put a plaster board screw in every single joist at 6 inches apart using almost 2000 screws then they paid for the ceilings & damaged walls to be skimmed flat again .

Initial water extraction for each dryer was in excess of 62 litres each machine every 24 hours. Final extraction when we moved back in was about 8 litres for both machines in the unoccupied dwelling .

 

[roofman]

Dig it out and concrete it with a propper membrane turned up the walls. That thick screed sounds like its turned into blotting paper.

 

[minimutly]

Does the block wall have a cavity? If not you will need to clad it to keep rain off, otherwise it will always be wet. Not so sure about the floor, depends what's underneath - neither my garages have a membrane, they are both dry. The one even has a rolling road in it which is also dry, and some of the rain we've had has to be seen to be believed..

 

[bricol]

Rent a tyrolean applicator and render the whole thing to make it water tight(er).

​

 

[addjunkie]

It definitely been rather damp lately in your part of the world @chunkolini . Any simple single skinned wall is going to wick water across it. It's worth using an aqua-vac, or a large broomstick-sized squeegee to get rid of the surface water in the shed, and go in and see where the water is coming in, next time it rains. It should become fairly obvious. There could be more than one point of entry, which might only be revealed after the main source is located and fixed. Might the door to the roadway, where the white van is parked, have something to do with it? Not sure of the layout you have there.

Im in agreement here, no matter how bad the floor is, if water is getting in, it will be damp. For a start there is no battens fitted around your door, is rain getting there.
Id probably render that being single skinned, water gets in through the smallest holes.

 

[dobbslc]

The blocks look soaked on the outside so that'll wick into the shed, you need to render it or at least slosh some waterproof liquid on them for now.

 

[gaz1]

i suspect it will be your window leaking in

no drip sill on the window fitted directly to block and concrete blocks are not water proof so wont help in heavy down pours as well as silicone dosnt stick well to most surfaces concrete and stone being one of them

you could if you wanted drill 1 meter drain holes in the outside wall as it does help to drain it

pic 3 i cant see an outside pic to other side of it so cant suggest blow under the doors but it could be an issue i cant really tell with whats on show

 

[chunkolini]

By the sound of it not a massive problem.
no cavity on the walls, solid blocks.
the floor is not erm exactly 'flat' see the nice water features where it pools.
I dont think its coming through the doors
@gaz1do you mean through the retaining wall to clear water from underneath? it is a hug volume of dirt beneath it.
oh the genius of the Moron. They skipped the old block shed and tipped in tons of whats it called? black shaley gravelly stuff into the massive hole
I had wondered about getting some kind of hole saw thingy and draining it into the large planter left of pic 2.
would tanking the insides of the walls help for starters? but the walls all appear to be dry on the inside. or put it on the outside? I know nothing. Google She say outside which makes sense to me
Im planning on getting it rendered but I quite like the rustic style of the blockwork. The moron has offered to do it; but he was told to get hence before I buried him.
my gut feeling is it's something to do with the shocking 'screed' he laid. This was his second attempt. I was away when he did it. There were umpteen sacks of sand and cement 'stuff' that had not set lying around the place.

 

[gaz1]

By the sound of it not a massive problem.
no cavity on the walls, solid blocks.
the floor is not erm exactly 'flat' see the nice water features where it pools.
I dont think its coming through the doors
@gaz1do you mean through the retaining wall to clear water from underneath? it is a hug volume of dirt beneath it.
oh the genius of the Moron. They skipped the old block shed and tipped in tons of whats it called? black shaley gravelly stuff into the massive hole
I had wondered about getting some kind of hole saw thingy and draining it into the large planter left of pic 2.
would tanking the insides of the walls help for starters? but the walls all appear to be dry on the inside. or put it on the outside? I know nothing. Google She say outside which makes sense to me
Im planning on getting it rendered but I quite like the rustic style of the blockwork. The moron has offered to do it; but he was told to get hence before I buried him.
my gut feeling is it's something to do with the shocking 'screed' he laid. This was his second attempt. I was away when he did it. There were umpteen sacks of sand and cement 'stuff' that had not set lying around the place.

solid single concrete block walls do leak if they are soaked enough

thompsons water repellent done every 2 years will repel the water away rather well or coat the block wall with a cover and drip edge as well

or alternative drip edge is there but that garage floor leaks water as it goes under the blocks due to a split under the blocks



ive had to grind at the door to create a drain so it can then go out again and yes water can be blown under the door if the concrete is at same level to outside

you ground will be hardcore filled but will fill up with water if no exit has been given just drill holes where your perps are ( concrete ups on the blocks will drain the land better if you have a meter drill it can deeper inside of the shed to help drain it but dosnt always need it )

the wall where your motorbike is stored you wont be able to coat but you can thompson water seal it though

 

[Afterimage]

If your roof had more overhang it would have kept the walls dry - I solved a similar problem with a 12" overhang on my flat roof.

 

[knighty]

Dig it out and concrete it with a propper membrane turned up the walls. That thick screed sounds like its turned into blotting paper.

scrolled down to post this but he beat me to it, new floor, new dpm is the only way you'll fix it

might as well paint the internal walls with damp proof stuff as well... then run the floor dpm a foot up the wall - that way they overlap and any damp should stay outside/behind/under the damp proof

 

[gaz1]

If your roof had more overhang it would have kept the walls dry - I solved a similar problem with a 12" overhang on my flat roof.

the window wall will catch the most wind swept rain when directed anyway so a long overhang wouldnt work