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Posted: Mon Feb 25, 2008 10:52 am
by yourgardenworks.co.uk
Alright Lads, firstly ive changed me sign in details from scoffsred to the one you can see so's i could include my website in me member name.
secondly, im planning to build a shed about 8 x 14 in me garden and the ideal place is under some trees, i say ideal but im not so sure about casting a slab over the roots of the tree which appear to be quite shallow, has anybody done this kind of job before and what should i do thickness wise etc ?
Cheers Dave
Posted: Mon Feb 25, 2008 5:52 pm
by lutonlagerlout
i would make a "floating " raft
i.e dig down as best you can,shutter the outline with wooden path edging lay 25 mm jablite (polystyrene) in the bottom ,then your DPM ,then 100mm of concrete with mesh and/or fibres
the idea of this is that even if the tree roots do lift a little the whole slab will move in 1 piece rather than crack
also the expanded polystyrene will allow for small movements
i'm no engineer but its how i would do it ,to avoid damaging the trees
cheers LLL 
Posted: Mon Feb 25, 2008 8:23 pm
by seanandruby
....Or cordek type cp for ground heave solutions.
Posted: Mon Feb 25, 2008 8:25 pm
by yourgardenworks.co.uk
Cheers Lads, what thickness for the concrete then ?
Posted: Mon Feb 25, 2008 9:12 pm
by Dave_L
Ya stupid b'stard Dave, I could have changed your username to suit, rather than you starting all over again!!
Posted: Mon Feb 25, 2008 9:15 pm
by yourgardenworks.co.uk
Dave_L wrote:Ya stupid b'stard Dave, I could have changed your username to suit, rather than you starting all over again!!
OOOooops sorry Dave, i should have asked, not like me too jump in feet first is it.
Posted: Mon Feb 25, 2008 9:44 pm
by Pablo
Another way might be to built the shed on top of a deck type subframe. Dig the posts into the corners to fit around any roots then a couple in the middle to take the bounce out. Use 150mm treated and 150x150 posts and it'll last as long as the shed and be quicker and cheaper than concrete. I've done it a few times over shallow rooted trees like cherry and pines and it worked perfectly. If you wanted concrete then stick with the plan above.
Posted: Tue Feb 26, 2008 7:28 am
by yourgardenworks.co.uk
The thing is Pablo, i will be building the shed out of box profile sheets and will be storing all my equipment etc in it so it will need a good strong base.
Posted: Tue Feb 26, 2008 6:31 pm
by Pablo
A properly built sub frame would take the weight no bother. May not stretch to a mini digger but everything else including the structure itself wouldn't cause any problems just make sure the holes are dug down to good ground.
Posted: Wed Apr 02, 2008 6:53 pm
by Riggers
I'm with Pablo on this one! would have a 'suspended' floor & use good joists.
Have fun...............Riggers