1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Shed insulation advice please.

Discussion in 'Building' started by MC76, 5 Mar 2019.

  1. MC76

    MC76

    Joined:
    5 Mar 2019
    Messages:
    10
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi all. I'm buying a 10' x 8' T+G wooden shed for the back garden and once built, the shed will sit on top of decking.
    I am planning on using this as a games room with arcade machines in. Because of this I need to insulate it really well so I have a few questions to ask if that's ok.

    1 What sort of insulation is best to use for this job? I am thinking of 50mm or 25mm Kingspan/Cellotex as while expensive it sounds like the best option after doing some research but I'm open to ideas.

    2 The frame in the shed is 50mm x 50mm so if I was to use Kingspan would I be best to use 50mm with plasterboard/ply straight over the top, or would it be best to use 25mm kingspan so I can have an air gap?

    3 What is the best way to insulate the floor?

    I realise arcade machines in a shed isn't the best idea as they don't like cold and moisture which is why I want to do a good job of insulting it in conjunction with running a dehumidifier and heat when needed.

    Thanks in advance for any advice.
     
  2. Sponsored Links
  3. blup

    blup

    Joined:
    5 Nov 2007
    Messages:
    992
    Thanks Received:
    143
    Country:
    United Kingdom
    Don't know about the floor but I think the advice is to put in an air gap if you can't get a vapour barrier under the cladding.

    Blup
     
  4. blup

    blup

    Joined:
    5 Nov 2007
    Messages:
    992
    Thanks Received:
    143
    Country:
    United Kingdom
    Meant to say breathable membrane, not vapour barrier which goes on the inner side of the insulation.

    There are plenty of posts on here giving more detailed advice.

    Blup
     
  5. big-all

    big-all

    Joined:
    12 Jul 2004
    Messages:
    17,728
    Thanks Received:
    1,328
    Location:
    Surrey
    Country:
    United Kingdom
    keep in mind your restricted to 2.5m above natural ground level the shed covers to avoid the need for planning if near the garden edge so include the ground to deck surface on top off you shed height
    also not a good idea to put any weight on top off decking unless so designed
     
  6. MC76

    MC76

    Joined:
    5 Mar 2019
    Messages:
    10
    Thanks Received:
    0
    Country:
    United Kingdom
    Thanks for the advice so far guys.

    Yes It will still be under 2.5m in height after allowing for the decking being raised 4".
    I'm sure the decking will be strong enough but I take the point and will look into strengthening it up to be safe.

    Has anyone else got any advice/answers to my questions? I have looked on the forum and other places but there is so much conflicting information and different opinions it's quite confusing and at least if there are different opinions in this thread I can ask questions without resurrecting old threads.

    Cheers.
     
  7. Alastairreid

    Alastairreid

    Joined:
    21 Nov 2008
    Messages:
    5,825
    Thanks Received:
    850
    Location:
    uk
    Country:
    United Kingdom
    Full fill between studs with 50mm insulation followed by 500 guage polythene stapled to the studs...tape any joints followed by either your plasterboard or plywood.
    floor i would lay a breather membrane, joists, insulation between joists, vapour barrier then flooring.
     
  8. MC76

    MC76

    Joined:
    5 Mar 2019
    Messages:
    10
    Thanks Received:
    0
    Country:
    United Kingdom
    Thanks for the reply and the picture. I've been away so only just got chance to reply.

    If I'm using something like 50mm Cellotex for the walls, would I need to add polythene over the top or have you used that because you're using a different type of insulation? And would the advice be the same regarding an airgap if using cellotex, would I want one or not?
     
  9. Alastairreid

    Alastairreid

    Joined:
    21 Nov 2008
    Messages:
    5,825
    Thanks Received:
    850
    Location:
    uk
    Country:
    United Kingdom
    If you full fill the gap with a rigid insulation and tape the joints you wont need the vcl.

    No air gap.
     
  10. Sponsored Links
  11. MC76

    MC76

    Joined:
    5 Mar 2019
    Messages:
    10
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi guys, had a bit of a hold up while I was getting the garden sorted. A few things have changed in the meantime.
    The shed is now 18' x 8' and it is built and in place. The first night it rained, water seeped up inside the shed between the tongue & groove and 3x2 timber in a few places.
    Now I think the reason this happened is that the water was dripping from the roof and bouncing straight up back into the shed. So I have now fitted guttering. It rained last night but the guttering seemed to do the job as it was dry this morning.

    This leads to my question. As this is an area where rain could potentially get in again if the rain is very heavy and on a certain angle. Is there a filler of some kind I can use on the outside underneath to seal the join where the T+G meets the 3x2 timbre? A waterproof silicone that sticks to wood would be ideal but impractical as you can't see what you're doing under there and very little space. Filler would be easy to use but I imagine it will crack and fall out or is there a type of filler or other material ideal for this situation?

    Any advice greatly appreciated as I want to crack on with insulation but need to be sure I've got this sorted first. Heres a pic to show where water seeped in. Cheers. 20190811_101507.jpg
     
  12. MC76

    MC76

    Joined:
    5 Mar 2019
    Messages:
    10
    Thanks Received:
    0
    Country:
    United Kingdom
    Here's a pic of outside with arrow pointing to where I'm thinking of filling/sealing so any rain bouncinguo in future won't find it's way in up through the wood. Screenshot_20190813-170232_Gallery.jpg
     
  13. big-all

    big-all

    Joined:
    12 Jul 2004
    Messages:
    17,728
    Thanks Received:
    1,328
    Location:
    Surrey
    Country:
    United Kingdom
    as your damp is on a corner inside
    check on the outside theres a baton or other timber to cover the end grain and gap between panels
    if the splash back persists try a 45% angle cement bead say 2" wide or a temporary bit off timber along the ground
    better to stop the water getting there in the first place
     
  14. MC76

    MC76

    Joined:
    5 Mar 2019
    Messages:
    10
    Thanks Received:
    0
    Country:
    United Kingdom
    When you look under on the outside you can see the edges of the tongue & groove floor and the bottom of part of the 3x2 batton. So yeah, quite a bit is vulnerable to splash back.
    It wasn't just one area of damp inside it was quite a few in similar places. I've used sticks like sh!t adhesive/sealant underneath as it sticks well to wood and is waterproof so it's all completely sealed now so hopefully that will sort it but I may put a batton under there as well.

    This photo was taken earlier before I added the sealant underneath. As you can see, it's dripping wet. Screenshot_20190815-235010_Video Player.jpg I had also earlier ran a bead of silicon across the bottom of the batton as you can see in the pic.
     
  15. big-all

    big-all

    Joined:
    12 Jul 2004
    Messages:
    17,728
    Thanks Received:
    1,328
    Location:
    Surrey
    Country:
    United Kingdom
    to be honest the very last thing you should do is add sealant or other to stop moisture escaping at the bottom as it will cause more rot
    better to stop moisture reaching the base but leave it breathable
    wood will only rot at about 19% moisture content above or below it will suffer but not rot
    its better to deflect or remove the moisture hitting the base

    indeed ii built my shed in 2005 the glazed door is cheap softwood it has only been coated with primer and nothing else
    it gets the weather many times a year but is fully sound and untouched by decay as its not sealed
    if you think about rot on doors and windows its always at the bottom rail because paint will seal in moisture so it cant escape better to let it breathe and it will last longer
     
  16. MC76

    MC76

    Joined:
    5 Mar 2019
    Messages:
    10
    Thanks Received:
    0
    Country:
    United Kingdom
    Ahh crap, ok I understand now.

    I was going to ask you exactly what you ment by a 45% concrete bead but the heavy rain coming I felt I needed to act fast and do something that I have the capabilities of doing as the sight of water penetrating the inside of the shed is very alarming.

    I really need to get on to insulating but can't do that until I have seen proof that no more water is coming inside.

    I know you are right on what you said about letting the wood breath but I was thinking that with it being a tongue and groove floor and cladding with little holes here and there that there hopefuly will still be enough air circulation for the wood to breath. I will be using 50mm cellotex and leaving a 20mm airgap on the walls and can leave an airgap on floor to if that will help the wood breath a bit more to make up for my mistake. Also, as it will be used as a games room I will be running a dehumidifier whenever needed to pretty much keep a constant 55% humidity or whatever is needed so hopefully there won't be to much moisture being blocked from escaping. What do you think?
     
    Last edited: 16 Aug 2019
  17. big-all

    big-all

    Joined:
    12 Jul 2004
    Messages:
    17,728
    Thanks Received:
    1,328
    Location:
    Surrey
    Country:
    United Kingdom
    dont worry too much about the silicon it wont do any damage as there is plenty off surfaces around for moisture to escape
    if your timbers are on the concrete you need to raise them off by at least a few mm if possible
     
Sponsored Links
Loading...

Share This Page