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shed foundations?

velvitjester69

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#1
Im building a home cinema in my garden lol.

Its gona be 4 metres wide by 5 metres long.

My idea for this was to build basically a fancy shed on top of a concrete slab base.

Im unsure of 1 thing.the damp proof course and membrane.

so I am planning to dig a trench about 6 inches wider than the shed ( ie,4 m 6 in on one side and 5m 6 in on the other,its gona be about 6 inches of hardcore,with an inch of sand on top of that.

On top of that I was going to lay a damp proof membrane and then put kingspan insulation and wire mesh on top of that.

Then fill with concrete ,so should have about 5 inches of concrete in total,with insulation and mesh taking up the middle.

what exactly do I do with the damp proof membrane then,at this stage it will be sticking up from around the concrete slab?

do I fold it back around and lay a course of blocks on top of it or just cut it off?

also are these plans ok?
Dave
 

benny59

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#2
Im building a home cinema in my garden lol.

Its gona be 4 metres wide by 5 metres long.

My idea for this was to build basically a fancy shed on top of a concrete slab base.

Im unsure of 1 thing.the damp proof course and membrane.

so I am planning to dig a trench about 6 inches wider than the shed ( ie,4 m 6 in on one side and 5m 6 in on the other,its gona be about 6 inches of hardcore,with an inch of sand on top of that.

On top of that I was going to lay a damp proof membrane and then put kingspan insulation and wire mesh on top of that.

Then fill with concrete ,so should have about 5 inches of concrete in total,with insulation and mesh taking up the middle.

what exactly do I do with the damp proof membrane then,at this stage it will be sticking up from around the concrete slab?

do I fold it back around and lay a course of blocks on top of it or just cut it off?

also are these plans ok?
Dave
you dont mention if your shed will be brick or wood m8 ?????{obviously im assumeing your shed will be wood,---"because you dont put the damproof membrane edges outside the perimiter of a brick shed"---- for that matter you dont leave a concrete slab with a membane open to the elements


a good base should be about an inch or so smaller than the actual size of your shed{on all sides}and perfectly level---you dont want rainwater trickleing down onto the concrete m8 {you will forvever be cleaning off the moss----"takes longer to dryout because of the membrane"}------pointless putting a membrane in concrete if water can get in through the top dont you think ?


so make your base an inch or so smaller than the shed {all sides}--"wait for the concrete to harden and leave the membrane edges uncut at this point"

get yourself some edgeing stones for around the perimier of the base {engineering brick is the obvious choice m8, "but pricey} half bullnose would be nice

dig a small trench around your base {making sure not to damage the membrane {8 inch trench is more than enough}--"now add about 3 inchs of concrete, makeing sure the membrane edges are held down on top of your slab with some bricks etc {now sandwhich the membrane between your edgeing stones and the slab with some sand/cement}==="make sure the edgeing is flush with the slab

wait till the edgeing goes off then trim the membrane

do you get my drift on the above m8

basicly your membrane edges will be under the shed nice and dry like the whole slab {the ony thing getting wet will be your edgeing}

biggest mistake i ever made was makeing my shed slab bigger many many years ago
 
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Munkey

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#3
As benny59 says, your concrete should be internal. The DPM will just run up along the walls before you cut it and just fold it away under your flooring. Use your engineering bricks as a rough guide to how high you should leave your DPM when you cut it originally.

All in all a very exciting project. Please keep us updated if you have time.
 

velvitjester69

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#4
thanks for the replies guys.

{now sandwhich the membrane between your edgeing stones and the slab with some sand/cement}==="make sure the edgeing is flush with the slab
Could you elaborate on this part benny,im not exactly sure what you mean.?


Maybe a description of what this would look like will help.
Basically its gona be a conservitory but made out of wood and not pvc,but I think the same construction methods will apply.

looking exactly like this,except minus the pvc

http://www.wikihow.com/Build-a-Conservatory

Maybe I should add that im basically gona build the shed walls on top of a single brick layer the whole way around the base.obviously leaving a gap of no brick where the door is gona be.

so the brick would be like this

http://www.buildingsuppliesrus.co.uk/product.asp?id=9566&aid=&aguid=&b=&guid=

and then basically build a stude framwork in 4 sections and hopefully construct that in a day,

so it would look like this

http://www.horizonhomedevelopments.co.uk/images/construction.jpg

except the brick would be like above and only however high the brick is on its side.

Im then gona use a damp proof course layed on top of this brick before I put my stud walls on top,to stop moisture getting into the wood.



So this made me think,would it be better to dig small foundations for the walls,build up with the brick above,so it is for example a foot high and then inside this wall then build the base with membrane etc?like how they construct a house extension?

thanks for the help so far.
Dave
 
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benny59

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#6
thanks for the replies guys.


Could you elaborate on this part benny,im not exactly sure what you mean.?


Maybe a description of what this would look like will help.
Basically its gona be a conservitory but made out of wood and not pvc,but I think the same construction methods will apply.

looking exactly like this,except minus the pvc

http://www.wikihow.com/Build-a-Conservatory

Maybe I should add that im basically gona build the shed walls on top of a single brick layer the whole way around the base.obviously leaving a gap of no brick where the door is gona be.

so the brick would be like this

http://www.buildingsuppliesrus.co.uk/product.asp?id=9566&aid=&aguid=&b=&guid=

and then basically build a stude framwork in 4 sections and hopefully construct that in a day,

so it would look like this

http://www.horizonhomedevelopments.co.uk/images/construction.jpg

except the brick would be like above and only however high the brick is on its side.

Im then gona use a damp proof course layed on top of this brick before I put my stud walls on top,to stop moisture getting into the wood.



So this made me think,would it be better to dig small foundations for the walls,build up with the brick above,so it is for example a foot high and then inside this wall then build the base with membrane etc?like how they construct a house extension?

thanks for the help so far.
Dave

So this made me think,would it be better to dig small foundations for the walls,build up with the brick above,so it is for example a foot high and then inside this wall then build the base with membrane etc?like how they construct a house extension?

yes m8, {dig your foundations 1st, then construct the floor from inside 2 or 3 courses if its brick- or1 or 2 courses of block}---this is the proper way to do it

foundation/width/ depth depends on a few things, {soil type/construction height and weight

not forgeting the foundation brick or block needs to be of the engineering type for below ground

http://www.thomasarmstrong.co.uk/NetBuildPro/process/26/FoundationBlocks.html?PHPSESSID=da5a8d674
 
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benny59

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#7
Could you elaborate on this part benny,im not exactly sure what you mean.?

forget about the top post m8, {that type of base was for a wooden shed only}

by the way {your not building a shed--------its a conservatory
 

bilabonic

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#8
See my thread as well mate on my 'shed' build . Need to add some extra updated pics but coming along slowly.
 

velvitjester69

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#10
cheers lads.

The shed is actually for a mate of mine,I said I would give him a hand,so just wanted to clarify first:)
I dont know if he will let me post up the pics,but if he doesnt mind then I will.