Robsco1

Do love a good bit of science Yeah, it's evaporating fine while the cavity is still open, and extra air gaps created between the bricks, my concern was when it becomes a sealed cavity, and how the moisture would get out then.

We're having a garage built with a cavity wall, window frames were left exposed when it rained, and now we have damp insulation in the walls below the window frames. Clearly evident from the white salt coming out of the mortar a metre below the window opening (and not on any other walls, or away from the window frames), and darker vertical sections of mortar, only below the window frames. I had a feel in the cavity and the fiberglass was damp to the touch as far down as I could reach - to the sides was still dry. The walls don't have any ventilation/air bricks of any kind, so I'm worried how long this will take to dry out on its own. Questions are: 1. Should I let this air out completely before closing the cavities? ie leave the windows out and make sure no more rain can get in. 2. How long may this take? 3. If anyone tells me this is normal and it'll dry out on its own, are they bending the truth slightly? ie, would it take 6 months. I'm currently using small timbers to help create some space between the fiberglass and the brick. The builder has done a runner, so we just have the roof to get on - doors are going to take another 4-6 weeks anyway, so leaving the insulation out of the rafters for now, and waiting to seal the cavity is no problem. Thanks, Rob

I'm asking the builders to include a breakdown of materials in their quotes, so I can at least see if I could get the bricks and blocks cheaper, as I prob have more time to shop around - my concern is then if I'm missing some feature of the materials that's important.

Hi all, I'm currently getting quotes from builders for trench digs and foundations, built up to DPC. Is there any benefit or risk in buying all the blocks and bricks myself, or do builders tend to get better discounts? Also, when looking at a few places for trench blocks, they seem to range in price from £7 to £10 - from what I can tell all the same dimensions and load capacities - is there anything else I should be looking out for, before simply going for the cheapest? £6.50 https://www.emerysltd.co.uk/300mm-3n-mannoklite-trench-blocks-yellow-band-24-per-pack-20010272?gQT=1 £10.50 https://www.turnbull.co.uk/product/-/40656?gQT=1 This one for £1.50 per block looked rather out of the ordinary. https://www.cornwhaul.co.uk/bricks-blocks-concrete-products/300mm-trench-blocks?gQT=1 Thanks, Rob

It's safe to assume I wouldn't be doing this. The door will also be well insulated. The point is to create a nice warm workshop all year round - woodworking, 3D printing, electronics, etc. ie, not to do a half-arsed job and only insulate half of it and be kicking myself later on.

Money isn't the main concern, I'd just hate to get in there and regret not insulating the floor. If I were to insulate the floor, I was also considering that the insulation would be better above the concrete, so I'm not spending time/energy heating the slab before the insulation gets to do it's thing - especially when it's not heated 24/7. If the insulation were to go on top, perhaps with joists and an OSB floating floor, could this all still be done up to ground level? ie with the DPM holding everything in and coming up above ground level?

I must admit this insulation is making me nervous. I'm currently in a single skin garage with 1 infrared heater, and it's kinda bearable. Would you still insulate the roof and walls? but just not the floor? This could also turn into a workshop for the missus doing sewing or anything, so we want it to be very comfortable. Maybe the walls and roof is already overkill?

Hi All, I'm building a new detached garage to use as a workshop. The new footprint will be 3.8m x 7.4m and wants to be insulated for the occasional times it's in use - I have an infrared heater which worked reasonably well in a previous un-insulated single skin garage, so will probably use 2 of those at either ends. The overall build will probably be brick/block rendered to match the house design, with an insulated cavity, followed by another inner block wall, with ply over the top. This will be a workshop, so *probably* no cars. Question one: My first focus is the floor, firstly whether to go for a slab or footings plus slab - I think the soil is quite sandy where I am, so understand that a slab/raft may be better, rather than having to dig (and fill) down so far to get past the sand? Question two: I think putting rigid insulation on top of the concrete would make the most sense from a heating aspect, to save the concrete absorbing all the heat before giving any back into the room - especially as it won't be heated all the time. Would joists and a "thick" OSB floating floor be ok, or is there a risk of damp or anything else?