Thread: Water/damp getting under walls

IMHO I think I would be looking at pulling up the pavers and pouring a good concrete slab. Even if you fix the damp coming under the walls the chances are you will be getting rising damp through the pavers, and they still will be uneven...not the best work environment for woodwork.
The other thought is if you are planning stud walls inside for lining, you might be able to solve a few other problems getting rid of the existing shed and start over,

Is it possible to get a few short sheets of wall material and slip them between the sheet and rail to extend down past the bottom openings? If a trench was dug about 150 mm deep and the strips put in, it should help the water getting in.
In regards to the gaps under the door, is it possible to remove and replace the frame to lower it down to floor level? These are what I would be inclined to do to remedy the situation.
To help prevent moisture getting into the pavers, lift them up and put down the plastic sheet, at the same time leveling them, if the other remedies aren't workable.
Kryn

Rather than muck about trying to patch things now it sounds like it would be best for you to bite the bullet and install a proper floor.

If you want a stump/joist floor you will just need to make sure the final level of the floor is 50 mm or so above the wall sheet bottom that is highest above the ground.
You should also try to keep the water away from the stumps on the low stump side of the shed.
A set of concrete or plastic drains set into the ground below the wall sheets that run along the two low sides of the shed should fix that.

At the doorway you just need to extend the floor out past the edge of the door way and add a door seal. Or add on a porch?maybe - that's what I'm planning on my shed. I hate standing in the rain fumbling with door locks.

If it were me I would just put in a concrete floor with a 12.5 mm polystyrene barrier between the edge of the slab and the wall.

Something I should have mentioned is that the moisture that's getting in appears to only come from rain hitting the walls and running down to the external bricks and soaking (not running) inwards. Mostly the damp area inside extends in only a couple of inches with one spot that comes in about 8 inches. The rest of the place is bone dry.

The property has endured flooding rains (and I mean FLOODING - I couldn't get to it for a couple of weeks due to surrounding roads flooded over) and there was barely any increase in the moisture that got inside the shed. It's pretty well drained around the perimeter.

Does that info help with anything?

As much as I'd like to rebuild the whole thing and put in a proper slab it's not really an option unfortunately. It's a big shed (6m x 9m) and besides the cost, there'd be trouble getting a mixer truck in amongst the trees (which admittedly should probably be cut down anyway).

I really do appreciate the slab suggestions and I know patching isn't a good solution but it's pretty much all I can do, particularly time and budget-wise.

I'll mention again that the pavers are only temporary. They are only staying down at the moment so I'm not walking on dirt and making a dusty mess. If it helps with anything, they can come up earlier, but by the time the flooring is being done they'll be gone.


KB's suggestion of extending the walls down is appealing. How well does the gal survive if it's buried though? Could I get away with using the dampcourse instead of gal as long as it's buried in firmly/vertical and attached to the wall securely?

BobL: The flooring was going to be another discussion, but if it helps here this is what I was thinking just at the moment...concrete in a grid of post anchors (rather than timber stumps) to hold the bearers (pressure treated timber), adding joists and finishing with yellowtongue. I could probably get away with just concrete "tiles" laid on the ground, or simple skids, instead of the post anchors but as the floor will probably need to support the walls (and possibly ceiling frame) I thought the anchors would be better suited for stability and easier to get level across the whole area.

I'll be wanting the floor to be as low as I can manage but suspect it's likely to come up at least half way to the bottom horizontal wall rail by the time it's done...which isn't a problem...the height is only a preference.


I like the porch idea too btw.

Originally Posted by RedShirtGuy

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The flooring was going to be another discussion, but if it helps here this is what I was thinking just at the moment...concrete in a grid of post anchors (rather than timber stumps) to hold the bearers (pressure treated timber), adding joists and finishing with yellowtongue. I could probably get away with just concrete "tiles" laid on the ground, or simple skids, instead of the post anchors but as the floor will probably need to support the walls (and possibly ceiling frame) I thought the anchors would be better suited for stability and easier to get level across the whole area. .

That sounds fine and should solve the problem.

Originally Posted by BobL

That sounds fine and should solve the problem.

Well, I wasn't expecting that!

So, just to make sure I've understood properly...if I do the floor the way I've described above I don't need to worry so much about stopping the moisture at the base of the walls? The bearers may only be just above ground level but as they're pressure treated they should be ok and/or I could staple black builder's plastic over the ends/bottom half of the bearers for extra protection against moisture.

If so, that's great news. I'd probably still do a little something around the wall base just for peace of mind and improve the already good drainage (earthen gutters) but I'd be very happy if I can solve it all just by doing the floor.

Please say yes, please say yes, please say yes...but truthfully

Just having a look at floor stuff and there's a couple of different heights I should be aiming for with the floors.

The bottom of the covering, the yellow tongue, should be a min. 400mm above the ground OR the bottom of the bearers should be a min. 150mm above the ground. I presume that's for airflow so it doesn't promote rot. So concreting in the post anchors might be out depending on what I can find locally that's not just a saddle on a stick of rebar.

I'll need to go to the shed to measure that over the weekend and see how much internal height I lose with both options and will keep hunting out more info - probably go annoy my old carpentry teachers at TAFE.

Just thought I'd chuck that out there while I'm thinking about it.

Can you raise the whole shed a couple of inches?

Rather than extending the gal down into the ground I'd personally prefer to look at trenching around where the pavers are and pouring some decent foundations. If you make the found's wide enough, you're also leaving yourself the option to run bearers & joists off the inside lip at some future date.

On [i]top[/] of the found's I'd like to run a course of mud, the damp-proofing and a course or three of bricks (pef. with liquid damp-proof in the mud mix... eg Bondall Dampcourse) then drop the shed back down onto these.

'Tis a lot of work, but should still be cheaper than pouring a full slab... and let's face it: a building is only as good as the worst part of it's foundation.


Option 2: remove the cladding, nail the damp-proof along the bottom of the frame so it'll hang over whatever you replace the 'pavers' with and into the ground... then replace the gal. Probably the cheapest way out of all possibilities (you did say you already have the damp course?) but I wouldn't go bragging about it in the 'pub where any building inspectors may be listening in.