Ticky

Hi all, I need to level out an area so I can place a shed onto it. Currently, there's a 3m squared area that's about 40-50cm deeper than the rest of the land. I was about to order enough MOT to fill it but then remembered I may be able to use broken concrete to build up first. I'm sure I've read that if I wanted to build up the foundation I could lay some geotex fabric down, lay some bigger aggregate (I've got some concrete slabs I could break up) followed by some MOT and compact along the way. Is this correct? Also, I'm unsure if the fabric was supposed to go as the first layer directly onto the undisturbed ground or as a second layer after the large aggregate. Thanks in advance

Ok, think I'm gonna use a soakaway for the above. Seems like a reasonable option I'm about to order my insulated roofing panels today. Been speaking to a guy at ColourCladProfiles and they seem to have the best price and include all the guttering/fascias etc. Plus there's a Coronation discount (that ends today) that knocks off the price of the delivery which'll save me £180 I know I don't even have the concrete poured yet but it's a 6 week wait on delivery anyway Hope you're all good

For the french drain would I be good allowing for approx 100/120mm around the perimeter? I'm thinking 60mm PVC pipe and enough room to surround it with pea shingle? Do I need to worry about the back of the Room which will be up against the neighbours fence (and have the guttering) would I just feed that gutter into the f-drain? Also, can I terminate the french drain into another part of the garden as I don't think i can route it to my existing rain water drain of the house.

Thanks all Another thing I'm not so comfortable with is that layer of pea shingle. I'd feel better if it was a layer that would compact better so could I use gravel as long as it has no fines? Would that be a problem? Tree stumps completely out now so can start leveling the area finally!!

Wouldn’t this prevent me from levelling the concrete? Unless it was ‘added’ after the shuttering was removed. 😂😂 Just a guess. What size would be suitable?

Why do you feel that EPS isn't strong enough? I thought EPS was designed for heavy loads similar to XPS

That's the image that I was looking at and couldn't fully work out. What purpose does the notch have? That seems like it would be a lot of effort to cut out a notch for every stud. Wouldn't the OSB finishing to the top of the upstand do a similar job? Like this? (corrected my previous attempt)

I'll take a look at that..... My plan was to go down the rendering route as discussed in this post More specifically this link in that post

Apologies, but i'm struggling to visualise again. Is that an extra strip of insulation? and I thought the sole plate was what the studs were attached too. Part of the wall frame? (I'm probably wrong again ha ha) Not really, just thought they looked better. Didn't realise you could get Aluminium ones that looked like bi-folds.

Also, want to have bifold doors. Are there any considerations I need to make when fixing those to the concrete? Do they need to be on plastic packers to prevent cold bridging or can they be fixed directly to the slab?

I was thinking.... as I'm going to have OSB + double battens and then cladding extending the depth of the walls, does that not give me wiggle room to bring the timbers more over onto the concrete? Even if it was by an extra 25mm, that would mean 100mm of the wall is over the concrete with only 25mm over the upstand. Any issues with that? I drew it out but missed out the OSB layer.

@saveasteading - my original idea included PIR but I was later informed both by the guys on here and a vendor above, that PIR isn't suitable for a raft.

Tell me about it!! ha ha.

@Nickfromwales You say heat it 'somehow' - you feel it's not going to be easy to heat with anything 'above' the concrete? @saveasteading I'm definitely open to options when it comes to fixing the threaded bar/bolts - think I've seen the epoxy approach on Oakwood Garden Rooms. My concern in drilling once dry was that i'd be close to the edge of the concrete and don't want to cause it to 'blow out'. If I have 5x2 soleplate, 50mm is covering the upstand leaving 75mm over the concrete. Image below is to scale. Would aiming to fix the threaded bar, in the middle of that 75mm (approx 37mm in from the edge) be about right? And how deep does it need to go? I'll have to make sure I'm not hitting any rebar/mesh too

Yeah it will be unheated. It’s going to be used as an office just by myself. No great plans for the flooring. I even thought of it being a polished concrete finish (or something similar) As for the roof, I was also planning on using insulated roof panels (again to increase head room) I believe these are pretty heavy (13.3kg/m2)

Why is that? Is that because it should 'self level' in a way? I'm struggling to visualise that.... would that be 1 row of verticals? and then 4 long horizontals going round the perimeter to make a rectangle?

Also, not sure I got the question about levelling/compacting the pea shingle. This is the bit that I’m most nervous about as most other concrete slab foundations look like they sit on type1 and sand. Paranoid as I don’t want to mess this bit up obviously.

Thanks, I actually thought they were the same thing. What should I be looking at is it the A142 type? with mesh spacers to hold them up?

So, how does this look? Any tips on the size of the piping used for the drain?

Thanks @Mike - so it sounds like crushed hardcore could be pretty much anything that's around 40mm in size. Where would I buy pea shingle that's guaranteed to have no fines? No one seems to mention it in the descriptions and I don't wanna buy the wrong gear I'm based in Manchester, so any pointers on where to source bulk bags of the above would be great @Iceverge @IanR @Temp Thanks again for everyone's help so far.

Hi @Temp I'm not going with that design now. I'm following the one both @IanR and @Iceverge landed on. See ian's post above. I'm going to draw out my full design this weekend and I'll share on here

Amazing - thanks @IanR I'm struggling to see the difference between crushed hardcore and MOT type 1. When I'm searching for prices on bulk bags they both seem to be coming up detailing crushed aggregate sizes 40mm to dust. Links to the right stuff would be really helpful. Also, would I still be using a compactor on the pea shingle that sits under the slab? I'm also not having much luck finding 10mm pea shingle that specifies 'no fines'

Thanks @Iceverge I've just educated myself about the different types of aggregate (you lost me on that too ha ha) and came across this blog and the guy seems to make a lot of sense (echoing a lot of what you said) Do You Need Gravel Under Concrete Patio, Slab, Footings? (plasticinehouse.com) Sound like using at least a 3 inches of gravel (20 - 25mm in size) should do the trick - would you agree? One other thing that got me thinking..... Both the designs from @Iceverge and @IanR included a 'step' with the 2 layers of EPS, making the concrete deeper beneath the walls. How would DPM lay over this 'bump in the middle' without there being lots of creases etc? Does the weight of the cement take care of any air gaps?

Thanks - I might be getting confused here. I was expecting to be digging down to a level then dropping & compacted hardcore/type1 layers below the pea shingle? Is that not needed when using EPS? I'm also lost here too. Sorry.

@Iceverge this hole was 600+ deep.