My garden office

[Mike7898]

I am building a garden office at present and have laid a concrete base which will be just smaller than the finished shed size. My question is will I need to raise the shed or can I lay the floor directly on the concrete base?

 

[big-all]

assuming its within 2m off the boundery keep in mind the need to keep below 2.5m to avoid the need for planning
if the base will be dry then say slate and dpm or felt under joists would stop moisture transferrance

 

[Mike7898]

Yep thanks for that I have noted it previously. Just the issue of weather I could put the floor direct on concrete as it’s a raised pad and will be smaller than the actual shed size by an inch or so. By slate do you mean roofing slate?

 

[big-all]

yes anything really a brick a slab is just in case you get water under there iff your struggling to keep the roof down using a slate and felt would mean you could get say 2mm of water and joist will still be dry
or a part slab say 15mm you would never get wet unless you had a massive hollow exceeding that amount

 

[Mike7898]

After colluding with a joiner today he has told me as my concrete pad is raised from ground level I could build my stud walls directly on them and overlap my membrane past the concrete? Will this work?

 

[big-all]

do you have a dpm within the concrete if not you may or may not get damp away from the edge also concrete is fairly industrial and can be cold underfoot

 

[Mike7898]

I have a dpm under the concrete yes. Could I not build my walls directly on the concrete then allow an insulated floor on top of the concrete inside? It’s a 20x10 shed so ideally hoping not to need to lift off the concrete

 

[big-all]

properly done you'll be fine as long as any water dropping off the bottom off the wall will only ever hit the base below the base dpm level

 

[Mike7898]

Thankyou really appreciate your time

 

[big-all]

make sure you plan it with gutter and access to clean out so your timber never ever touches earth or any build up off leaves or detritus can be removed every so often to stop decay