jpadie

Thanks @Dave Jones and apologies for delay in replying. Am 500km away from home helping my youngest daughter move after completing uni. There are currently 10mm floor boards down on 35mm battens going to the floor joists. A few of the floor boards (4) have the last 50mm with dry rot where they were touching some other joists that had rotted over 50 years. The rest are good. I'd intend to replace the perished boards. In your schema would these serve instead of the 12mm osb? I don't think I can get to the old boards easily to coat the underside without ripping them up... But as said, after 50 years they are still ok except for a small area of a small number. Taking the boards up is an issue as the ends rest under the wall frames and I'm not keen on fully dismantling the shed unless all other routes are barred! It's sturdy and rot free apart from one area of issue, and still largely true to square.

It will have an ashp. There will not be a concrete slab wherever I restore or rebuild (I am certainly rebuilding one side frame). Does this mean that the floor cannot be practically insulated?

Work shed to an office. Void above the dirt is not damp. Plenty of air flow. Timber joists sit a few inches above the earth. Unfortunately where they end they sit on bricks and have perished. I am replacing them and will hang them on joist hangers going forward.

All good points thanks. This is for a garden room conversion. Small surface area of 12sqm. The base construction is joists over a void to earth. Supported on a ring of bricks. There's not much headroom (1m80 from the joists) so I'm trying to work out what the minimum practical layering over the joists would be. There are current 10mm floor boards resting on 35x35 battens over the joists. There is no DPM at present. What's the optimum here, taking into account that this will never be the Ritz? Leave the boards in place, dpm on top, jablite/something then chipboard then floor finishing?

Hi all Can I lay jablite directly over floor joists, then top with chipboard before the finish? If so what is the maximum span for 50mm panels please? Thanks Justin

I started getting into the shed conversion yesterday and found that the floor was being maintained only by chipboard. The floor joists had rotted away. I pulled everything up and found that one wall of the shed was no longer supported at all and in several places had rotted through. What's the option here? Get some pressure treated lumber and some tile or brick and Jimmy things back together? Replacing the floor beam and rotten joists? Or is it demolish and rebuild? The aim is to have a decent garden office that will live for 5-10 years. Thanks in advance photos available here https://photos.app.goo.gl/YTLvVADym9viCSCn7

Thanks for the response @Temp The floor is 50mm square sections resting on brick going the width of the shed. On top of that there are 35mm square sections going lengthway. Floor boards on top of that in some of the shed. Board on other sections. When you say remove the insulation and replace with foil backed foam are you suggesting packing the foam between the joists or attaching to the face of the joists?

Hello all I mainly tinker with microelectronics and am a little out of my depth with construction. But I'm going to plough on come what may. Before I make too much of a Horlicks I'm hoping for a couple of bits of advice. Briefly there's an existing 4*2.5 shed that I want to convert to a garden office. It's been standing 60 years or so. I've yet to pull up the floorboards but it looks like it is sitting on bricks on the earth The wall studs are all 50mm deep. Overlapping horizontal wood cladding onrhe outside. The roof is felt on OSB with some timber joists. It's not got any support from the apex to the eaves so I need to add some struts. Probably 2*4s There is some poorly stuffed mineral wool insulation in the wall cavity at the moment. No breathable membrane but there is heavy plastic sheeting on the inside of the cladding (stapled to the inside of the joists which leads me to believe it was added as an afterthought. No insulation in the roof and the windows are barely present. I'm looking to put some foil backed foam on the walls (50mm) and ceiling (100mm). Then some thin osb then drywall. The reason for doubling up is to allow a bit more flexibility in installing shelving and desk units etc. Does this seem sensible? Is the plastic sheeting "good enough" or should I pull down the cladding and put tyvec up? Will the felt suffice in lieu of a breathable membrane? I could put tyvec up on the inside of the osb if not. Floor: I'm thinking of jablite with chipboard and then some engineered light wood or similar. I'm unsure how to fit the jablite at the moment as I suspect that under the floorboards there is a void to the earth. So nothing to bed the jablite onto. Not sure whether there is a common workaround for this? Windows will be replaced with double glazed pvc units. I will post again for these as I am not sure how to measure up yet. I'm struggling with the door too as it is currently very short and I cannot see any off the shelf product that offer small doors. By the by I'm thinking also of installing a reversable mini split with an air-water heat pump for heating and cooling. Probably a 2btu size but TBD. Anyway that's enough questions for now. All thoughts welcome!