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Hello,

We have recently been having an outhouse / gym built at the end of our garden. Unfortunately, things did not work out with our original builders and we have had to start looking else where to get the work completed (so far the shell has been completed). On getting new quotes from other companies, we have been told that no DPM was put in place when laying the original foundations and the incorrect blocks were used for the first run around the building (breeze blocks have been used from bottom to top). All in all meaning that damp would rise, and it would probably be best in the long run to knock the building down and redo it properly.

I've read up online about dpm and how it should be done, and can only see a thin sheet of it placed between the first and second block, but nothing else. The original company have mentioned black jacking it, but is this a viable solution?

I've attached some images. Any help or advice on the situation would be really greatly appreciated. I don't want to have to knock the building down, but in the same way I would rather make sure it is done correctly rather than have a temporary solution.

Thank you!

I am no expert: Need to straighten the facts: you have a DPC after the 1st block is this repeated on the inner blocks?
Are the blocks on the concrete slab and are you sure no DPM was put before the concrete pour? see this video for the DPM sheet https://www.youtube.com/watch?v=oN_dXm6j44s
If there is a slab is it the finished floor, if not a DPM could be added now, it won't be as good but if lapped up the 1st block would stop most problems.
There are many buildings erected without DPC or DPM and the many YouTube without DPM testify to that but it depends on the local water table and any rising ground levels nearby.
For sure the wool insulation should not start below the DPC as it will act as a wick to any moisture that gets in below the DPC and transfer it up.
If you need to meet building Regs or for an NHBC then 1st course of breeze blocks is not suitable. However these look like Aerated masonry concrete or ‘aircrete’ blocks which are very light weight, crumbly and about half the strength so used mostly for their insulating properties on inside walls. Are there metal wire ties between the two courses of blocks?

Hi @aeromech3 - thanks for your reply!

-- Yes from what I can see, the layer of material is on both the inside and outside walls.

-- Yes, the blocks are straight on the concrete base that was filled. There was already an existing base to the right of where the builders laid the cement, so I cant comment on what's in there. In terms of what is in the concrete they laid, I remember wire mesh and stones going in, but don't really remember seeing any material / dpm going in. That's not to say there isn't, I just don't remember seeing any going in which doesn't really help the situation.

-- The current floor isn't final as its not level. We were told it would need to get screed?

-- In terms of metal wire ties, there are some very thin wires that look like they are holding the insulation in place.

I've attached some photos of the base as it was being laid at the end of each day - possibly that can help shed some light? I've also attached one of the current state of the project - its been like this for 10 weeks now, so i'm concerned 10 weeks of British weather would have seeped into the blocks already, so any dpm measures would be too late. I'm not sure if the blocks dry out though, so it would still be ok? They do look a very saturated darker colour in places.

Thank you again for your reply!

Well only my opinion:- of course starting the build correctly would have been best; taking what said so far, I think it is worth a gamble, the existing fence will keep most of the weather off the blocks, The front opening span, has it a metal lintel holding the one line of blocks?
If the insulating wool is Rockwool, mineral wool, look for a used bag and not fibre glass wool or other, it is less likely to wick moisture, as I can see it would be difficult to remove the bottom layer. Before the final floor screed or levelling compound, a DPM should be used, this could be liquid or sheet but should extend up the 1st block ( can be hidden by some deep skirting board or if not too fussy can use soffit boards).

Exterior render or cladding should help keep the rain moisture at bay - many single skin buildings are built this way as well as correct use of guttering and drainage.

A sheet of dpm layed on the concrete slab with the final floor be that concrete or floating floor layed on top. Similar to how garage convertions are done.

ah

Thank you both for your replies!

Good to know there are some options with what we can do.