Having trouble building a shed base.

[Mark A]

Hi,

I am having a bit of trouble building a shed base. I decided on a 2" x 4" pressure treated frame, but I was going to sit this onto piers to lift it off the ground. Only trouble is that I have bought medium density concrete blocks, that I have now found out wont do as they crumble over time :/.

I bought ballast and cement to make concrete and was going to dig out 8 holes, 4 each side, then put the blocks onto the concrete pads. Then sit the timber frame on top of this.

Is there anything else I could do? I don't really want to spend any more money on this if possible. I'd also like to use the blocks up some how. Maybe smash them into hardcore?

The shed is fairly large at 10' x 8' and the site its going on is turf at the moment, with clay soil under.

TIA

 

[Mark A]

I was going to go for paving slabs but with the soil being heavy in clay I was advised I would have had to put a thick layer of hardcore down. So that would mean a lot of digging out, having to get rid of the topsoil, having to buy a lot of hardcore and then having to buy the paving slabs. Would have also had to hire a wacker to compact it and my local tool hire charge £45 for the day.

Just seemed simpler, cheaper and quicker to use pier foundations and a timber frame. Just wish I had read up properly and got a suitable material for the piers.

Keep to your plan,

bed and render the blocks in sand cement mortar 1/2" all round, this will weatherproof them. Some old quarry tiles on top or a thin steel plate to provide a bearing and spread the load.

That's a good idea. I didnt think about rendering them. I dont have any materials for on top to spread the load though, so If I have to go and buy something I may as well just buy bricks or something and use them instead.


One Idea I did have was to dig out a trench the same size as the timber frame. Then fill it with the all in ballast that i ordered to make the concrete. Then sit the Timber frame onto the ballast. That way the ballast would provide drainage so the timber isnt sitting on damp ground.

The timber is pressure treated so should last a while before it starts to rot. I do also have some pvc trim that i could nail to the under side to help stop water getting to the timber.

Would this work?

 

[Mark A]

My shed, not as big as yours at 8' x 6' sits on a 4" x 2" treated (tanalised)timber frame on ballast so that the base of the frame is at ground level. This has worked for about 8 years. The shed floor is 4" above the ground. We had the same ground, thick clay. I placed a 6" layer of ballast, then levelled the frame on blocks, then tamped ballast around the frame and blocks using a 4" x 2" pole with a piece of 9" x 3" nailed to the end

Thanks. I might give this a shot then. If the worse comes to the worst it wont be too hard or costly to replace the treated timber frame if it did rot.

My old shed was just sat on red bricks, directly on top of the soil and that lasted a good 15 years . It was a lot smaller though at about 5' x 8'.

 

[Mark A]

a good tip, even though the base of the shed is already pressure treated, i always give it another coat of fence paint, its not going to be seen.

Thanks. I have some Ronseal shed and fence treatment. I was wondering if you could use that over the top to add more protection, so its good to know you can. The shed I have bought is also pressure treated so I'll probably give that a coat as well.

 

[Mark A]

Here is a shed me and mate built from scratch last year on a base, granted it was easier because we had slabs to build on but could get the same base with hardcore/rubble to keep things level and such.


Edit: Sadly I don't have a picture of the completed thing.

That is one strong base! Looks great.

Hmm, that gives me an idea. What if I was to dig the holes for the concrete pads. Then make up some 1' square by 4" timber frames and sit them on top of the holes, then fill in the concrete up to the top of the timber. So it would be just like using the concrete blocks but it would be solid concrete instead of the blocks.

Would I be able to smash up the concrete block to use as hardcore?

 

[Mark A]

I would do 4 concrete piers using sonotube forms and strongtie connectors, like this:

I think what I'm planning to do is similar to this, albeit on a much smaller scale.

Something i just noticed in that article:

I always suggest that buyers of my storage shed plans check with their local building inspector to make sure which method of anchoring your shed floor is acceptable in your particalar locality.

Do you have to get planning to build a shed in the states?

 

[Mark A]

Ok, this is my idea instead of using the concrete blocks to sit the frame on.

I have made some timber shutters out of the crate that my blocks etc were delivered on. I will make 4 of them and then lay them out on the grass where I want my corners to be and level them. Dig the hole about the same size as the frames, then fill the holes with concrete. Lay the frames over the top and then fill to the top with concrete and scrape it off so its level with the shuttering.

I'll use 6 of them, 3 each side. Does this sound ok? Its all I can think of without having to go out and buy more materials.

Also does anyone know if I could smash the concrete blocks up to use at the bottom of the holes as hardcore? or I could use some of the ballast as I got loads of it. I have a few red bricks and some stone I could mix in.

 

[Mark A]

Great! Glad I don't need to buy any more materials as I have spent a fortune so far.

As for securing the timber frame to the pads, I was thinking of making some L brackets out of some aluminium chequer plate I have lying around. Then screwing it to the concrete pads using concrete screws. But wedge anchors would probably be better. I'll pick some up soon.

Now I just need to find something to do with these 16 medium density concrete blocks I bought .

 

[Mark A]

You'll need a lot of concrete to fill that shuttering

What happened to attaching a timber frame to foot square piers?
That would be a lot easier to get level before you built a shed on top.

You can get cheap U shaped brackets that cement in, they use them for fencing but supporting a timber frame is much the same idea.

That's what I'm doing. That frame is 360mm x 360mm x 70mm, which is a little more than a foot, but I just used the length of the concrete blocks as a guide.

I will make them a foot sq actually. I have 18 bags of ballast and 3 bags of cement which should be enough but i'd rather not have to go buy more.

 

[Mark A]

Got the frame slapped together today. I used 2 together for the middle as there will be a concrete pad in the middle at each side so that should add some strength.

I'll probably put some of the blocks i got under the beams in the middle to take any bounce out of them. They should be ok under the shed protected from the weather.

Used these to fix it together. So much better than using screws.

I didnt quite realise how big the shed was until the base went together. Hope 6 concrete pads will be enough..

 

[Mark A]

Its 10' by 8'. Hope I can get away with 6 though as i have put them 2 joists in the centre of the frame. I'll see what its like after pouring the concrete for the corners.

The floor of the shed has what looks to be 2" by 2" runners, running the length of the shed and then there is 16mm T&G floor boards on top of them. So I'd imagine that the floor runners would help spread the load a bit.

I'm wondering whether to dig a couple more holes in the centre to take any bounce out of the frame. Or maybe just jam some concrete blocks under.

 

[Mark A]

I have dug out and poured the concrete for the 4 corners and I'm also going to put some concrete pads down the centre to make 9 total, on the advice of mp260767. If I have to buy some more stuff I will as id rather it was right.

Would it be a good idea to bed the frame onto the concrete pads with some sand and cement? Or just pack it where necessary and then screw it down with L brackets and concrete screws?