help with lean-to extension

28 Dec 2014
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United Kingdom
hi hope you are well and thanks in advance.

i have a little project i want to do - i want to make a lean-to down the side of our existing extension.

i want to put a washing machine and tumble dryer in it amongst other things and so it needs to be kept reasonably above freezing. i dont really want to heat it so it will need to be insulated. what i dont want to do is cut out all the light that comes in through the existing external door into the dining room (see pictures) - so i would like to make the whole roof clear if possible (but also reasonably well insualted). ive seen polycarbonate roof sheets to do this but dont know how good they are at actually keeping in the heat.

i could also put in a velux style roof window or two but that will be time consuming and expensive and want to avoid if possible - also im not amazingly competent at diy so i want to make it as easy as possible. if i can piolycarbonate the whole roof that would be much easier - much fewer changes of materials and junctions between materials.

im planning to put a wood frame on concrete footings or maybe just lintels and then insulate the floor. i can insulate the whole left hand side wall as it will have cupboards on it and wont be see through (hence the need for light from the roof).

im thinking to remove the gutter on the existing extension extension on the right hand side and run the new roof under it (it has flashing there already). i want to get the shallowest angle i can to avoid the door but also go under the black round boiler exit (and i will need to get some kind of plume management kit for it i realise) - see pic below.

any thoughts please either on the roof material or the general construction idea?[/img]
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Well. I assume you won't be telling building control about it.

What are you going to build it out of? wood?
In that case it could be considered a shed.
you're wasting your time insulating it if you're not going to heat it
(which tenically you can't heat it) as it's not actually part of the house.

Plastic sheeting does not give any insulation at all. It's intended for shed and greenhouses.
The only way you can do that is have a plumber relocate the flue to at least another brick course or two higher. Otherwise it won't work, it's smack where the end bar will be. To be honest the door is going to cause a problem too it's quite high. If you changed the door for a plastic one and had it opening in then you could do it. Otherwise this is going to be a problem job. We fit loads of lean to type jobs like these and I can see this one being a pain. Sorry to pee on your fire.
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the builder who put it in said he could just put a right angle on it, run it up the wall and fit a plume management kit on it - that likely to be ok?

i can get enough angle i think between the door, the gutter and the outlet for the boiler. i could also make it so that the left hand wall isnt vertical all the way up and angle it in a bit?
To fit the poly on the extension you'll need a wall plate to sit the bars on. The top of the wall plate needs to be at least 2 inches from under the tiles. You need to get a straight line drawn on the bricks, you might just miss the flue. No don't angle the wall in, everything will need to be straight.
ok thanks for all the advice.

anybody got an answer for the roof material though? (clear but insulating)?
ok great. i will do.

regarding the boiler output - what if i just got it extended horizontally along its current course along the the length of the extension and had it terminate at the new "back" door? its about 3 meters. i could then put the roof line above the existing exit point?
thanks stef - doesnt it have to be x meters from the roof, from windows and things like that?

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