Double Garage Build - East Sussex

#1

Over the last couple of weeks I have finally started to build my studio! (design thread here:http://spartanew.digistar.cl/Forum/viewtopic.php?f=5&t=19) Beginning with mundanities such as removing rawlplugs, screws, nails and other fixings from the brickwork / woodwork while marking where I need to back fill with mortar, I moved on to stripping out the old wiring and neon lighting.

A temporary power supply was rigged up by an electrician, so now there's nothing preventing me sealing the existing walls. I commissioned a steel flitch plate to reinforce the existing beam and the work was carried out by a local fabricator (to an excellent standard I might add - it was engineered to millimetre accuracy).

Before it could be fitted the supporting ‘pier’ needed attention because it wasn’t quite as tall as the one at the opposite end of the room . When the beam was originally installed it was levelled by packing the gap with blocks of wood(!!).

So props were placed under the beam and the packing removed, meanwhile engineering blocks were cut to size and cemented in place.

By tomorrow the mortar should be firm enough to take the last prop away and that’ll be the main structural reinforcement done!

#2

Yay! Out of the blocks!

It’s fun trimming engineer bricks : )

If we’re packing mortar anywhere we use any size bit of wood to ram it in...fingers at times... gloves of course ; )

#3

It's looking pretty good, John! Great work.

- Stuart -

#4

So, full of newly restored enthusiasm, I set about sealing the outer leaf walls. To do this, I intended to fill the numerous drill holes in the brickwork and then apply two thick coats of masonry paint.

The filling part was easy enough and I left the mortar harden overnight.
One of the mistakes I made in planning this build (it's a rapidly increasing list) was assuming that because the garage is built in to the earth at one side, this was a good thing. It has to be, doesn't it? WRONG!!!!!! For months now in SE England it has been raining non-stop, almost with no let up. Overnight it was particularly bad, really knocking down to the point that the ground surrounding my house is completely saturated (there is standing water on the lawn). Inevitably, rain water has found it's way into the garage. The chalk line in the photos indicates roughly where the ground level is on the outside of the wall.

It seems to be coming up from the ground between the slab and the bottom of the wall on the side that is below ground level, not soaking through the brickwork but this is a major problem. It will take weeks for the walls to dry out (assuming it stops raining soon which is a big 'if') and I have to work out what to do in order to stop it happening again. Could the building be partially tanked? If anyone has any helpful suggestions, I'd love to hear them!

#5

My garage in The Chiltern Hills is similarly situated into a bank and I have had your problem. As a little bit of water won't hurt in a garage we had to dig a trench between the garage and the earth, up the side and across the back, and then we slottled into that gap sheets of GRP. That has reduced water ingress by probably 95%. In your case you need 100% so a similar approach would the same except that you would need to seal the edges of the panels so that no water at all can get through. You need to cover down to the damp proof course, if there is one. If you don't have a damp proof course then specialist expert advice is required.

In your instance, rather than GRP, maybe self-adhesive roofing felt, with self-adhesive flashing covering all edges, plus swimming pool liner, sealing each layer so that if one should fail there is still the second waterproof layer in place - belt and braces approach.

#6

That's sad news, John. As Starlight said, it might need major surgery to fix that, from the outside.

I'm not sure if you are following Tom's thread about his build, and how he sealed up his place, which is also partly sunk into the ground, in a very wet area: his garden is actually subject to flooding very few years, so he has had to take special precautions, including getting the building tanked. You might want to talk to post a link on his thread to yours, with a question for him to take a look, or maybe PM him. Perhaps he could recommend the company that tanked his place, or at least let you know what the process was like, and how much it cost.

But one way or another, it looks like you need to do something to get that problem solved.

It doesn't look like your walls are wet, though: maybe just the bottom course or two, wicking up the standing water?

Also, are you sure that the water came in through the walls/slab? Maybe it just leaked in under the garage door? I really do hoe that's the case, as sealing up the door is a lot easier than sealing up the walls and slab!

Oh, and Tom used a blowtorch to help dry out his walls fast... I'm not sure if that's an approved way of doing it, but it worked for him! Might be worth looking into...

- Stuart -

#7

Thanks for your reply Starlight. I think this will take a lot of work to resolve and I not even sure I can afford to do it. If I can, there is a damp course around the concrete slab in my garage so I think what you have suggested could well work. Another possibility would be to install 'weeping' tile (or a French drain as it's sometimes called) along the outside of the wall. Either way it means excavating tons of heavy, clay soil and that's going to be very expensive!

#8

The water is definitely coming in through the small gap between the slab damp course and the wall. I'm going to call a drainage company tomorrow but I suspect my budget is blown.

#9

John Steel wrote:Source of the post The water is definitely coming in through the small gap between the slab damp course and the wall.

That's a real bummer, John. I do hope there's a simple, inexpensive solution.

One thing I would suggest when you get to building the inner leaf, is to use pressure-treated lumber for your sole plates, just in case they do get damp. You don't need it for the studs or the rest of the framing, but it would be wise to use that for the sole plates. They are a little more expensive, but not much, and well worth it. Sealing the wood of the sole plates, in addition to using treated lumber, give you an extra level of protection against water.

Also, use mineral wool insulation for the wall cavity, not fiberglass. Mineral wool holds up better if it gets wet. It keeps its shape, and does not sag. Fiberglass, on the other hand, ends up as a soggy mess! Even though the normal recommendation for studio walls is pink fluffy, which has good performance for that application, in your case it would be smart to use mineral wool.

- Stuart -

#10

Hi John,

So sorry to hear of the damp through the mortar where the DPC is!

I personally didn’t favour external tanking, though I’m sure it works well. Our trench sides were not favourable and kept collapsing so we couldn’t do anything on the outside...not to mention the rain flooding in!

I used ‘Construction Chemicals’ Tanking slurry. It’s fibre reinforced polymer blah de blah cement based with accelerated set. You can apply it to damp substrates as long as there isn’t running water affecting the mix ratio for the initial set. Check their guidance and procedures of course but from memory:

Tanking slurry is in 25kg powder mix maybe 1/3 a bag at a time as you don’t want to rush it too much and it sets in the bucket in about 25mins in 10degree temps I reckon. Mix using a paddle mixer/attachment on a drill. £50 a bag but you probably don’t need many bags.

Brush apply horizontally coat of no more than 3mm (how you judge that I don’t know). Apply to internal face to a height of 1m above external ground, Thats the industry reckoning for capillary action vertically) and down to the floor covering the floor to wall join well and onto the floor 500mm minimum horizontally.
Install 25mm ‘fillet’ (45 degree angled wedge) of mortar 1:4 cement to sharp sand (holme sand) to wall to floor join after initial set of 1st coat (could be end of 1st day).
Finally apply second coat using vertical brush strokes.

Should work, it did for me, but I will say that I have two masonry walls not touching both internal faces tanked.

I only really don’t like external non breathable materials because I like the external face to be able to breathe... I love true lime work on buildings.

I will also say, if it’s not a large section of wall, maybe dig a spade’s width of the mud out on the outside of the wall, drop a pipe with holes in at the bottom, place a fleese like material against the vertical mud and fill trench with gravel, then you are pretty much belt n braces. I wanted to do it with mine but the trench sides were ropey and some were getting close to 2m which is very unsafe. 1.2m is the limit without shoreing the trench but people have been injured in less apparently... ramble over : )

#11

Thank you very much for your reply Purelythemusic,
This is exactly what I was hoping for. I have called a local drainage contractor who is visiting tomorrow to see if there is a solution to be found there, but it occurs to me that I should tank the outer leaf anyway, whatever else I do as part of a 'belt and braces' attempt to stop the water reappearing. Top man!!

#12

but it occurs to me that I should tank the outer leaf anyway, whatever else I do as part of a 'belt and braces' attempt to stop the water reappearing.

You certainly could do that, yes, but you'd have to stagger the two stages over time: you don't want to trap water inside the wall! So first do either the inside or the outside, then wait until the wall itself has dried out well (I think Tom used blowtorches to speed that process up a bit), then do the other side.

- Stuart -

#13

Soundman2020 wrote:Source of the post So first do either the inside or the outside, then wait until the wall itself has dried out well (I think Tom used blowtorches to speed that process up a bit), then do the other side.

Yea sort of... to be honest my outer leaf was pretty soaking when we did it but as long as you don’t seal the other side of the wall as well, instead let install the land drain with loose fill on top, then it should find a stable level of moist I think!
We used blow torches on the blockwork just before rendering the outside as the blocks were saturated and the inside was rendered so it would have trapped a bit in the wall...but also to aid the bond with the external render and increase the surface temperature so it didn’t take too long to set up. The roof was also blow torched to allow us to apply the primer to the concrete...all about the bond!

#14

Hello again one & all,
I hope you are all staying well and managing to maintain relative sanity! The recent re-availability of building materials has allowed me to make some modest progress on my build this week but before I get on to that, I think it’s worth mentioning something that might be useful if you’re about to start your own build - specifically that you can save a substantial amount of money by bulk ordering materials for delivery instead of relying on more local suppliers.
I set up several trade accounts with nearby timber and building yards and while it’s true that they beat retail prices by a good margin (10 - 15%), 10 minutes of internet research revealed bulk delivery sources that saved me £4 a sheet on OSB3, nearly £5 per sheet of MDF and over £6 per sheet of cement fibre board on ‘trade’ prices. The minimum order was £500 for the timber and £250 for the cement board, but given the quantity of materials needed to build even a small studio, it’s a threshold that’s easily crossed.

The first job I tackled was to tank the garage and I’m extremely grateful to ‘Purelythemusic’ (AKA Tom) for his steer on this. I applied a coat of Construction Chemicals tanking slurry (as far as I can tell it’s a mixture of cement and glass fibres) up to one metre above ground level (said to be the limit of capillary rise in brick walls). Then added a wedge of mortar (or ‘fillet’) around the perimeter of the room where the slab meets the wall. When the mortar had hardened sufficiently, I painted on a second coat and left it to cure (the manufacturer recommends a full week). Not my tidiest work, I confess but at least it will be hidden!

Meanwhile I raised the two joists nearest the gables to make room for the inner leaf silencers, moved another one other to create more space between the rafters and pinned the others with M12 bolts.

The raised joists will be reinforced (or ‘collared’) before any increased load is placed on them. Then I started to make a framework from softwood batten inside the gable timbers which is set in 30mm from the edge. I’m going to attach the Cement board and OSB3 cladding to this (after caulking it of course).

I originally intended to pin the boards directly to the gable but doing it this way will increase the inter-leaf cavity by the thickness of the cladding. Thanks for reading - more photos at ‘johnsteel.org’. Best wishes, John.

Soundman2020 - Studio Design Forum