JohnMo

You to start by making a decision - are you happy with the walls, if not get wall straight and true first. If happy with walls do it as it says start at back corner and work towards the door. Decide your datum wall, back wall would be my choice. Leave a gap all round for expansion, cut boards to wall angles, otherwise looking like a dogs diner comes to mind. Cover gap with skirting or trim pieces.

We struggled in some areas due to the amount of cables, we had 50mm everywhere. Any smaller than 25mm will be splitting as you fix them. 50mm or 11mm isn't going to make the room feel any bigger or smaller

Mgo has an A1 fire rating (non combustible)

The link on page one, do mgo skins - 2 hour fire resistance. https://www.sipsdirect.co.uk/product/mgo-sip100-1-2m-x-2-4m-x-100mm-panel/

Two L shapes 1.5 x 3m.

Glass ballastrade at decent prices and good delivery https://www.made2measure.co.uk/post-and-saddle-system/ Did a quick cost and it's about £1k for glass with posts Because if the fall is more than 600mm it has to comply with building regs. First bullet point in the attached.

Sorry not agreeing - I will bow out and leave you to it.

There is a how it works video in 18 hrs or something. It shows a cross section of the mini store and it's lots of coil inside. I am wondering if its more like a harlequin cylinder.

We had an air test done pre plasterboard, fixed all leaks, then on the final air test the guy just put tape on the room terminals, test was no better than the first test. So don't do that. Do as others have said and isolate the mvhr from the outside world.

Why wouldn't it apply the fall is there and is great enough that fall protection is required. Trouble is not doing it correctly, is just as likely to cause issues, same as not having there at all.

Are the sleepers pinned to each other and to the ground, or it gravity holding them there?

I built mine from pallets, on concrete blocks, floor covered in excess ply from the house roof, more pallets for walls, stuffed with left over insulation, excess breather membrane the outside, vapour barrier on the inside. The clad the outside in off cuts of larch cladding. Only thing I paid for was the roof corrugated panels. Pretty much free, except my time.

Basics are Any cross section of the house, take a pencil or your finger following the insulation if you need to lift the pencil or your finger, to keep following the insulation you have a cold bridge. Your glazing and doors are classed as insulation. Apply the same technique for the airtightness layer. If you are lost, post drawings and ask.

Welcome Plenty of users of MVHR on here not so many with hybrid heating. For a new build to install both heat pump and boiler would really be a waste of money. If converting from gas already have a nearly new boiler it may make some sense. Just install heat pump, UFH so you get low flow temps and cylinder with big coil. Set to work as a single zone. Cheap easy and low running cost. Just make sure you don't over size the heat pump to much. If you want more info on hybrid raise a question in the correct section.

So a bog standard small shed with 25mm PIR insulation on the inside. Sit the floor on plenty of blocks or plastic grid with gravel in it. No need for strip foundation or 8" of concrete.

What's going in the shed? Can't imagine anything that would require an 8" slab, my garage has a whole 4"

Why should that make a difference, worked with really great engineers of all genders, also worked with some really dumb ones mostly blokes.

Open it the day before you want to use it, if hard, get down to the shops and buy new. Or as @SteamyTea say just buy some more anyway. If the old stuff is ok, you keep the new tube for another decade or so.

I need to be more blunt and to the point. But at least he now knows he has a condensing combi boiler. He just has to figure out what the condensing bit means.

Best guess - If it's wet enough to come of the nozzle should be ok

Data sheets normally. So a bit long winded

The basics are A boiler has a rated kW output that's it's max output. It also has a minimum output. The difference between the two is the modulation range. My Atag combi boiler would do 34kW max and 6kW minimum. When the output was below 6kW it would switch on and off to manage the heat output. Short cycling is when a boiler starts and stop to quickly. What causes a short cycle. 1. Not enough water volume to carry the heat away from the boiler efficiently. You would add a buffer to meet this requirement. 2. Not enough flow rate. Both 1 and 2 are required. To support 6kW output without short cycling you need a flow rate of around 16L/min and over 50 Litres of water actively engaged in the circulation circuit. Not sure if the size of your extension if it's zoned etc, or the boiler you propose to use, but unless it's huge you are unlikely to meet the required min flow or volume for a combi boiler. Unless it's a Viessmann model (£1500 to 2000 approx) that can turndown to around 1.8kW.

Exactly the same for us

Couple of markups 1 this is a cold bridge, basically heat can find a way to cold as there is missing insulation. 2 adding Compacfoam will remove cold bridge. As there is now not a uninsulated pathway from warm to cold. Compacfoam is also able to hold structurally. 3. Your upstand unless quite thick is now a weak area heat will go down to the ground and outwards to atmosphere also. Upstand I'd around 50mm or more.

That just needs a spade in the grind to move some earth, take a photo and initiate. That's all our had done, on the day planning ran out. We then altered house and building methods. Are you actually building yourself, as in hands on? Or a self builder getting someone in to do the work?