concrete block shed

Hi

I'm getting some quoted for a 3m x 4m shed to be built at the bottom of my garden.

What should I be looking for in the quote? I want a shed that doesn't suffer from damp.

Is concrete block even waterproof?

Resistance to the elements is a standard feature of most buildings. When you ask builders to quote you need to be specific about;

1. What sort of floor you want (solid concrete is usual in a shed but not compulsory. You could have an insulated concrete floor if you wanted, or even suspended timber. Up to you)
2. Whether you want single skin or cavity insulated walls. Single skin is cheaper and quicker, cavity insulated will give you a warmer shed. Or timber frame is possible
3. What style of roof you want- monopitch, flat, ridged.
4. What roof covering you want- slate, tile, wrinkly tin, fibreglass
5. What level of insulation you want in the roof (none or lots)

Then get your quotes, ideally from builders who have done good work for acquaintances, and take it from there.

Most shed dampness is caused by condensation (water-laden warm air comes into the unheated building, at night the walls and roof cool down and water condenses on the cold surfaces). Tin sheet rooves are very prone to this. Insulation or heating are your 2 remedies- definitely insulate the roof (no need to go mad), walls if you want to but not as much of an issue. As long as there's a damp course in the block walls and DPM under the concrete slab (both standard features) then you won't get ground water dampness. Try and avoid building your walls on the concrete floor slab- there'll always be a bit of concrete outside the wall, rain falls, lands on concrete, seeps under wall into shed. Much better to do proper foundations then concrete the inside afterwards.

Main traps- make sure that foundations are included as well as removal and disposal of spoil, any rainwater goods and finishes like barge boards, fascia boards etc. Other things to think about- if you want a door or a window then best bet is to let the builder supply it/them- that way you have a single point of contact if anything goes wrong with them (if you supply and the measurements are wrong or they're not suitable for the walls then it's your problem).

Standard concrete blocks will keep the rain out but they are porous (so if you built a swimming pool out of concrete blocks you'd need to line it with something to keep the water in). You can reduce their porosity by painting them- again this will keep the rain out but no more.

Stuff to think about- where are you going to send the rainwater? Do you want power in the shed? Running water? (which would also mean drainage)

Or you could build it yourself........that sized shed (unless it is very high) won't need planning permission or building regs

What do you want the shed for? if its for storing garden tools then almost anything would do. if you want it for a music studio, model making man cave or office then it has to be insulated, as explained and also the floor, else your feet get cold. I could add if you want power points/lighting this must be specified. I actually doubt many builders would be up to doing this complete project properly.
If you are not a DIY geek, I would buy a suitable shed/ shed kit which can be finished to what ever standard you want then get a builder to do foundations that the shed manufacturers specify and put/install the shed on them
Frank

Thanks for the detailed advice. It has given me the information I needed.

The shed will be used for overflow storage from the house so food, clothes and all sorts of other items! It doesn't need electrics

The first quote I had the builder mentioned that he could do a single block shed but double would be better for longevity and keeping the damp out. He mentioned DPM and damp course in the concrete slab base. It would be a monopitch felt roof.

He also mentioned rendering? the outside.

You can build it with a single skin and design it to be resistant to penetrating damp, just as you could with double skin and cavity, but unless you heat it, it will always be susceptible to condensation damp.