New shed build - lining queries

[ajs]

I've just built a Forest Garden Beckwood shed, only 7x5ft as a mini home workshop. I'll do a full write up here in due course - I know I searched in vain for a reliable considered review from someone who had actually built it - but right now I'm still in the initial kitting out stage, i.e. electrics, lining and so on. It's the lining I'm seeking input on.

My plan is to skin the inside of the frame (walls and ceiling) with ply, probably 6mm as it looks like it will be a matter of £20 over 4mm and a bit more solid to mount surface sockets on. Would also hopefully stiffen up the shed a bit - I wouldn't call it flimsy but there is movement with a good shove. Does that sound reasonable? Screw or pin it place? With silicone sealant over the frame or without?

I'm inclined to fill the resulting void with lambswool insulation (Thermafleece) for environmental reasons and also because it is available in 25mm which will neatly fit between the framing. Any suggestions on holding it in place prior to the ply going on? Also do I need a breathable membrane, and if so open to suggestions and which side should it go on?

Finally, the floor. I had originally intended simply to paint the floor once the pressure treatment has dried. It's a solid timber tongue and groove floor but rather knotty in places - one plank is already failing because of a sequence of knots across the board. It looks like it will be easy enough to slide that out and I intend to contact Forest to see if they will send a replacement. However the rest of the floor is a little too spongy for my liking so I'm thinking of covering that in ply to spread the load out. 12 or 18mm? It looks like I can just squeeze the floor out of a single sheet with a sensible cutting plan but it's right on the limit.

Sorry for the length and thanks for any insights.

 

[LizBurg]

You've probably already sorted this out but FWIW my two pence would be if your eco-conscience will permit I would suggest 25mm rockwoll slabs cut to fit between the studs of your walls, they will be self-supporting whilst you get them in and are as easy to cut with a bread knife as they claim. If you are using a breathable membrane it goes outside the insulation to help keep the insulation dry from water penetrating from the outside. I have no experienmce with lambswool.

12mm more on the floor should be more than enough if you already have 12mm T&G boards. Moisture resistant chipboard probably best I would have thought without knowing what you have to stop dampness coming up through the floor. 18mm chipboard would be enough to go straight onto joists at 450mm centres so given you are already supported pretty much over the whole of the bottom of the new floor layer with the T&G 18mm would be overkill. I probably wouldn't even go as thick as 12mm if all you really have to span is the knot holes, though as they came out I would glue the plugs back in.

As for the thickness of the wall sheets and how to fix them, are you planning to hang things on the walls? If you are 4mm would probably be too thin, unless you are going to use french cleats screwed into the wall studs.

Screw or pin/nail? Nails are arguably better than screws at resisting sideways forces, screws are better at not pulling out. If everything will be on shelves and all you want the inner skin to do is stiffen up the walls, bead of adhesive and pin/nail should work, unless of course you think you might want to take it off again sometime!

Have fun