Building a block shed, advice please

CompNewb · 18-07-2010 5:43pm #1

Right the time has come to build a shed out the back garden. It is only going to be small, about 5m x 3m.

Now i want to use standard concrete blocks. What do you think of this foundation detail? The dround is fairly hard.

I plan on doing a sloping roof.

Would 100mm x 440 x 215 blocks be ok? And what about the floor depth? And foundation depth?

Thanks for reading

Corkey123 · 19-07-2010 12:31pm

Looks fine for a 4 inch solid block, though I'd put some half inch steel in the foundation. Little cost but piece of mind.

Question: Why not use 9" cavities. Easier to lay, a bit more forgiving than 4" solid. You could also re-enforce them if you have any doubts about the build Though you will have to wide the foundation to 18"

No mention of course damp course for floor nor block work?

jack of all · 19-07-2010 1:07pm

I'd second everything martincorcoran says and add the following:

4" blockwork is very thin and a 5m length of this would need a pier midways to strenghten it; far better to use 9" hollows, especially if you plan on having a monopitch roof. As a general rule of thumb the foundation should be 3 x width of the wall, so a 675mm strip foundation of 300mm depth would be appropriate. Walls below ground level should be solid blockwork, not hollow. Foundation depth should be 18" below ground level, to resist frost (think of last winter). May sound a bit OTT for a shed but this would be good building practice. Floor depth should be 125- 150mm concrete, on a DPM, lapped with wall DPC. Try and incorporate a duct for possible future power supply, it's easy pull a cable in down the road.

Carlow52 · 19-07-2010 7:24pm

outside ground level should be 150 below internal FFL

If doing y/self go 4" on flat on wider foundation: much easier than 9" hollow.

Plan ur opes and overall dimensions to make the requisite half block over lap easier.
If going 9" hollow use footballs { i/2 blocks) instead of trying to cut 9" hollows

CompNewb · 19-07-2010 11:42pm

Thanks lads,

I have taken all your suggestions on board.

It is going to be a fairly small shed so i was going to use 4" on edge to make as much space inside as possible. its only going to be 4m x 2m.

But the hollow blocks would give a more stable wall. Using 4" solid on flat as Carlow has suggested would mean alot more blocks....trying to keep cost to a minimum.

Anyway i have quickly drawn this up just to see what you guys think. What is the depth from the ground level to the bottom of foundation?? is it just when i hit solid ground min 300mm??

Oh and what would the chance be off shuttering the base slab of the shed and pour 90% of it at the same time as pouring the foundations so only get one delivery of concrete?? And then hand mix the reaming and fill around the edges...actually sounds like a crazy idea just typing it!! In total all i need is 3mcubed for founds and 1mcubed of concrete for base...

Thanks again, for some reason i cant thank your posts.

Corkey123 · 20-07-2010 10:46am

CompNewb

I'd use 4" flat on the foundation up to the level of the floor and 9" cavities from there.

Have you considered using steel mesh for the floor - what kind of weight/activity are you expecting.

Seems a good idea for a single pour, but you will have you hands full getting the foundation pour level regardless of mix. If it begins to go wrong on you then you could end up in all sorts of trouble - 4m2 is a lot of concrete - have help on hand if you go with that idea.

You can do the floor at a later time with an ordinary bell mixer.

300m foundation will be enough for a standard shed, as mention earlier a bit of 1/2 inch steel will help.

I think Carlow52 meant 1/2 blocks when building up from the foundation and not the whole build otherwise you'd will have built a nuclear bunker

paddy147 · 20-07-2010 9:35pm

Interesting info there.:)

Any blocklayers.brickies or builders here wanna give me a quote and possibly build a shed for me??

Im serious,let me know or PM me.Im in Dublin.Thanks.

CompNewb · 21-07-2010 7:02pm

Thansk Martin once again,

I will throw some 10mm mesh into base slab and maybe some of the same into teh found.

How long do you reckon it would take to build.....mainly just a DIYer myself.

Reckon i might give it a shot, have 2 weeks holidays coming up at the end of August.

i reckon i can build it for around 4000 with hard labour and friends....

Corkey123 · 22-07-2010 12:39am

Just finishing the block work for my own shed - almost at roof height

Sorry to say you'll need more than two weeks, though price is about right pending on door, window, roofing, etc.

Digging foundation and getting rid of the clay can be a problem. Access to and from the sight will also influence the time for build.

Getting the ground work done could take a week alone pending - though a small Botcat type digger would be handy.

Consider the weather also as it will have a impact on the timeframe.

Suggest you don't worry too much about time and concentrate on the quality of the work. A **** shed built in 2 weeks will be a **** shed in 10 years time.

kitchens decks · 07-03-2011 4:59pm

hi was just wondering how your shed went ... is it finished??? starting my own shed and was just reading up on the advice you took from others

paddy147 · 07-03-2011 6:17pm

done.

Corkey123 · 07-03-2011 10:41pm

Nice one paddy

Mine is finished from the outside. 16ft by 8ft as opposed to Paddy's which is huge. Sand,cement + terelyne finish. Just to sort out a few minor issues, but largely finished.

I'll post pic if I get me arse off this seat

harryoc493 · 19-06-2019 5:43pm

Hi guys I know this is an old thread but I am building my own workshop/shed and am just wondering about the walls I am using cavity breeze blocks but I am wondering if I need to put vertical rebar through the cavities and fill with concrete

bfclancy · 19-06-2019 6:14pm

harryoc493 wrote: »

Hi guys I know this is an old thread but I am building my own workshop/shed and am just wondering about the walls I am using cavity breeze blocks but I am wondering if I need to put vertical rebar through the cavities and fill with concrete

No, blocks are designed to work on their own

Calahonda52 · 19-06-2019 6:20pm

harryoc493 wrote: »

Hi guys I know this is an old thread but I am building my own workshop/shed and am just wondering about the walls I am using cavity breeze blocks but I am wondering if I need to put vertical rebar through the cavities and fill with concrete

Cavity breeze blocks????

bfclancy · 19-06-2019 6:29pm

Calahonda52 wrote: »

Cavity breeze blocks????

I presume he means nine inch hollows as we call them out west

harryoc493 · 23-07-2019 8:20pm

bfclancy wrote: »

No, blocks are designed to work on their own

Hi guys yes I mean 9” cavity blocks also I have never laid bricks before, am I taking a chance to be building this on my own. Do you guys think there is much chance it will fall down without rebar

bfclancy · 23-07-2019 8:59pm

harryoc493 wrote: »

Hi guys yes I mean 9” cavity blocks also I have never laid bricks before, am I taking a chance to be building this on my own. Do you guys think there is much chance it will fall down without rebar

No chance. Built hundreds of sheds this way. Drive on.

harryoc493 · 23-07-2019 11:11pm

bfclancy wrote: »

No chance. Built hundreds of sheds this way. Drive on.

Thanks for the response is there any specific order I should do the walls in? (Eg. corners first) and also could you give me any tips as I’m a first timer

harryoc493 · 23-07-2019 11:26pm

harryoc493 wrote: »

Thanks for the response is there any specific order I should do the walls in? (Eg. corners first) and also could you give me any tips as I’m a first timer

Also is there any kind of vertical support I should add to the wall as it’s going to be about 2.5 meters tall

bfclancy · 24-07-2019 8:33am

harryoc493 wrote: »

Also is there any kind of vertical support I should add to the wall as it’s going to be about 2.5 meters tall

Build corners and run in the courses in between using line and pins. It's a shed and has corners therefore no need for vertical supports. Finsih with a normal block layed on the flat for the final course as it is better for fixing the roof to

Metalrobe · 30-07-2020 12:44pm

Im building a shed myself soon. 5 metre width and 10 metre depth. Im going to go with two layer of blocks with a cavity in between if I want to insulate down the line.

Question is is a strip foundation ok for this sort of shed? I was going to pour the floor and powerfloat it once the block are built.

Any other tips are greatly appreciated. I have a block layer and roofer sorted.

jack of all · 30-07-2020 1:18pm

That's a nice big shed, a strip foundation is the norm for most blockwork walls, unless poor ground conditions or other factors are in play. It's good practice to put some steel reinforcement in strip founds , A393 would be typical. Rarely done in founds for a shed but it will give piece of mind and ensures against any cracking down the line. You should consider putting some insulation in the floor-anything is better than nothing at all. Lay on power and water connection- even if you don't think you'll need water run a an extra length of ducting out to the shed, if buried sufficiently deep you could run a water service through it later. Run one or two underground ducts for any external lighting you may want down the line.

Metalrobe · 30-07-2020 3:20pm

jack of all wrote: »

That's a nice big shed, a strip foundation is the norm for most blockwork walls, unless poor ground conditions or other factors are in play. It's good practice to put some steel reinforcement in strip founds , A393 would be typical. Rarely done in founds for a shed but it will give piece of mind and ensures against any cracking down the line. You should consider putting some insulation in the floor-anything is better than nothing at all. Lay on power and water connection- even if you don't think you'll need water run a an extra length of ducting out to the shed, if buried sufficiently deep you could run a water service through it later. Run one or two underground ducts for any external lighting you may want down the line.

That's perfect thanks. Ya I waste going to run some pipes to allow access for the pipes for the boiler and a waste pipe if I decent to put a toilet in it down the line. I may possibly use it as a home gym so no harm put some insulation in the floor alright.

Metalrobe · 09-09-2020 10:43pm

I'm actually going down the raft route and starting in two weeks. I'll throw up a few pictures when I start.

Seve OB · 08-10-2020 6:49pm

thinking that i might get stuck in and build my own shed as ive asked a few builders who just don't bother coming back to me. must be to much work out there and im down to 2 day work and 2 days golf! im pretty good at DIY, have laid a proper patio and a small garden wall around it before but that is the extent of my brickwork! I have put a roof on my dads concrete shed before and know i made a few mistakes, but its pretty solid all the same.

i see in an earlier post that the internal floor shouldn't be below the outside ground level. why is this? i was hoping to have a step down into my shed, about a foot so that would give me an extra bit of height inside it......i would like to go 10 foot clearance inside, maybe 11

would be interested to see how you guys are progressing

im going to start working on some plans, is there some sort of program anyone could recommend which would be useful?

Lumen · 08-10-2020 7:00pm

It's easy enough to get 11ft of headroom in a pitched roof shed without having the floor below ground level, you just need to be clever with the floor and roof build up and not waste space.

If you do sink the floor you'll be fighting damp ingress forever, unless your site is sloped enough to dig French drains round the edge and take water elsewhere.

I used SketchUp to design mine but it's slow work and a lot of the time pen and paper with simple maths is quicker.

Seve OB · 08-10-2020 8:02pm

Lumen wrote: »

It's easy enough to get 11ft of headroom in a pitched roof shed without having the floor below ground level, you just need to be clever with the floor and roof build up and not waste space.

If you do sink the floor you'll be fighting damp ingress forever, unless your site is sloped enough to dig French drains round the edge and take water elsewhere.

I used SketchUp to design mine but it's slow work and a lot of the time pen and paper with simple maths is quicker.

it won't be to big, about 3m*4m. Will probably be a mono pitched roof (if thats the correct term) with the higher wall at the front. 9-10 foot required at back,

you say damp ingress, would some sort of damp coursing not be possible?

garden is actually sloped, slightly, but drainage is non existent. very muddy soil, and once the winter comes, it just becomes a marsh. So i actually plan to do something about that also. will be a bit of landscaping involved and if it comes off the way i have it in my head it will mean that the front of the shed will be flush with the garden, but it will be the sides which will be a bit higher on the garden side. hard to explain, i'll have to get drawing!

have used sketch before, yes its slow, and i can't really remember how to use it so will be another learning curve. pen and paper might be better lol

Supercell · 09-10-2020 9:37am

Pics please lads once you do get started, want to do one myself but total newbie so watching here with great interest!

Lumen · 09-10-2020 12:12pm

Seve OB wrote: »

you say damp ingress, would some sort of damp coursing not be possible?

Normal damp courses operate above ground level, they're designed to stop damp rising.

DPMs under slabs are also designed to stop damp rising (into and through the slab), but are not designed to stop water passing through walls.

Below ground level you're looking at tanking internally, sealing exterally or simply putting drains round the perimeter to carry the water elsewhere (downhill!). Any water coming sideways or downward should simply follow gravity rather than seeping through the wall.

Drains require some maintenance and enough slope to get the required falls.

You're making things more complicated by going below ground, but that's what makes it fun, right?

Metalrobe · 10-10-2020 2:32pm

Just finished the raft two weeks ago and the blocks were delivered today. Blocklayers are arriving monday so wont be long before its up. 10m by 5.5m with a cavity wall. Not running any insulation but can pump it if i want down the line.

Building a block shed, advice please

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