Bottom edges of outside rendering

[Andy Dingley]

I now have a vast number of outside sheds, brick or breezeblock built, of varying ages. A small example is below:

Mostly these are rendered with some sort of roughcast, which goes all the way down to ground level. As this ground is poorly drained flat concrete and I'm in Wales, that's a recipe for damp inside and out. The guttering is sparse, so rain tends to shed straight onto the shed walls. There's no bellcast.

One of the sheds even has a bizarre "boot" of concrete(?) around the bottom edge, a brick-sized square wrapper around the outside foot of the wall. This isn't a plinth or a socle, as it's alongside (and outside) the wall, not beneath it. As a result, and because of it cracking away by age and movement, it actually traps water rather than shedding it!

So what's to be done?

A possible course would be to hack off the bottom few inches of render back to the brick, leaving a neat sharp edge as a partial bellcast. Below this, treat the bricks with bitumastic paint. Obviously any moss disappears too. I doubt thhat re-rendering to a full bellcast is worth it.

The boot goes too.

Any better ideas? Any favoured products for stopping minor penetrating damp in old refurbs, either inside or out?

Thanks

[BigWallop]

Is it possible to cut 4 or 5 inches off the render and install a bitumen paint and flashing around the brickwork of the sheds? As long as you gather a skirt that allows the rain to run away from the bottom of the walls, would it be possible for it run off to a drain Etc?

[Tim Lamb]

In message , Andy Dingley writes

How on earth do you get anything longer than 3'6" through those shed doors?

I was going to suggest creating a French drain along each wall with shingle back-fill but you are a bit tight for space. I suppose some very careful diamond saw undercutting might create a drip.

Maybe you should just clear roof it and keep the rain out altogether:-)

regards

[meow2222]

The bare bottom section of brick should be left bare. Waterproofing it only makes things worse. The aim is not to slow down the speed at which interior RH reaches equilibrium, but rather to shift the equilibrium point. A lot of people make that mistake.

NT

[BigWallop]

[Andy Dingley]

That's just the outside loo and the wine cellar

The real sheds are over here:

I was going to suggest creating a French drain along each wall with > shingle back-fill How shallow can you make a workable French drain?

[BigWallop]

Anything below the damp proof course in the wall is enough. Preferably below the footing, but as low as you can go should work. It's only to stop standing water lying directly against the walls.

[Tim Lamb]

More asbestos there than my entire farm:-)

I'm no expert.

When the farmhouse was *done up*, the exterior was re-rendered over 25mm of insulation. The plasterers used expanding metal edging and formed a drip so I don't have water trickling down the brick. However, yard and soil levels had been made up over the years and are well above the existing slate damp course. I wanted to create a large patio and decided to build this at dpc level. To avoid bridging problems I laid 6" concrete edging between the house wall and the patio and then filled the gap with shingle. It is roughly 6" deep x 12" wide, on free draining soil and goes all the way round the old part of the house. The rising damp problems my mother endured over 50 years have gone:-)

regards

>

[Andy Dingley]

The what? 8-) This place was built in the 1880s and the further shedlet here is some nasty jerry-built (and I mean that relative to the general nastiness of shed bodges) add-on in the '20s. We're pretty poorly served for "damp proof" anythings.

Thanks, that's an interesting idea. I don't think I'm going to go with it here on the narrow bit, owing to future planning around dog crap-related issues, but it's a neat idea for the bigger open spaces around the big sheds.

Presumably a french drain is going to involve digging a rock-filled pit for a soakaway too? I'm restricted on where else I can send the runoff to, as there doesn't seem to be any drainage provided (the few gutters have downspouts that just empty onto the ground).

[BigWallop]

The what? 8-) This place was built in the 1880s and the further shedlet here is some nasty jerry-built (and I mean that relative to the general nastiness of shed bodges) add-on in the '20s. We're pretty poorly served for "damp proof" anythings.

Even in the 14th Century they had slate damp stoppers in the bottom of walls. Make sure there is no damp course in the wall, or even a slate flooring slab in the footings, and that the soil around the buildings has not been built up passed it over the years.

Thanks, that's an interesting idea. I don't think I'm going to go with it here on the narrow bit, owing to future planning around dog crap-related issues, but it's a neat idea for the bigger open spaces around the big sheds.

Presumably a french drain is going to involve digging a rock-filled pit for a soakaway too? I'm restricted on where else I can send the runoff to, as there doesn't seem to be any drainage provided (the few gutters have downspouts that just empty onto the ground).

Some were actually just a deep pit, like a moat, to stop water lying in hard packed soil against the outside of the walls. Because the pit is filled with larger stones and rubble, the water soaked down easily and either soaked through the surrounding soil naturally, and the outer side of the pit was kept lower than floor level to stop flooding into the house as well. That's about the length and width of a colonial drain (French Drain, Moat Drain, Chinese Pit Etc. Etc. Etc.) :-)

[Tim Lamb]

In message , BigWallop writes

Having looked again at picture 2 it is more of a shed than a garden:-)

The guttered bits appear to be collecting and dumping the water back into the slot. Elsewhere you have barrels/butts but no obvious gutter.

My thought for the day is to route the collected water to butts (in the wide bit) and use some 1/2" hose to drain the butts to a soakaway dug in your *lawn* as far as possible from the buildings. The soak does not have to store much as that is the purpose of the butts.

You can route the hoses through those shallow French drains you were going to install. Their secondary purpose is to stop rain splashing onto the walls.

regards

[Andy Dingley]

All I appear to have is a single course of blue engineering brick, laid badly with substantial mortar gaps to bridge the DPC. Oddly these bricks seem to have been laid at 45=B0 (flat, but wider when viewed from above) so as to provide a wider foundation for the single skin wall. This then provides a further "rain catcher" step above the DPC!

The later outbuildings don't have anything visible, but then they're just very shoddily built.