oranjeboom

I have a vaulted roof, and wondering how best to insulate it as there is a section of the roof that won’t have any ventilation at the bottom of the rafters as there are no eaves. Difficult to explain, so let’s for the sake of keeping things on topic assume it’s a case of semi-detached houses – one has vaulted roof as in the pic below. No eaves therefore along the central valley. My construction so far is: Slates battens (50x 25mm) Breather membrane 175mm rafters My plan was to: fill in between the rafters with insulation (full fill with 200mm), leaving no ventilation gap as I have no ventilation pathway at the bottom of the rafters (i.e. valley). Taped joins. VCL Insulated Plasterboard NB: I don’t need a service void (will be using uplighters) If I fully insulate between rafters and ensure the VCL is carefully taped up along all joins, should there be much condensation risk? I have breather membrane on top of rafters and the ridge is ventilated, so warm air beneath the tiles has an ‘outflow’ at the top at least. Internally, I will have MHVR. As for insulation, I need to check u-values but was thinking of going for PIR as my rafter spacings are irregular in any case so would have to cut whatever I use. May as well improve u-values and use PIR rather than Frametherm. Probably a bit more of a pain cutting PIR to size, but would foam in every crevice/gap, then add VCL carefully. I have considered using foam (icynene) but concerned contractor will bodge it up with too much uplift of breather membrane. And also the cost is an issue! TIA!

It's quite a large area, so I think I am having to go for 4 loops here, so I'll make sure that I have a loop each side of the 'divide'. Good thinking! : )

Thanks Ian. Something new to consider then. It will be one continuous slab, all with meshed UFH. Finished floor will be bamboo. So if there is any movement between the two areas, then i guess it's best to induce that along this 'line'. Best to do a wet cut 20-30mm deep? Just wary of cutting the UFH loops! Probably best to do this when cured which will be harder to do but safer.

Yes, movement wise I don't think anything is going to crack. It's a 60mm gap which will be covered by 300mm EPS70 plus 100mm meshed concrete. I just feel the need to fill it as there were mice in the attic previously....could potentially eat their way down the cavity insulated walls elsewhere and then travel along the footings and then up into the EPS layer. Not sure whether they have much of an apetite for EPS.... I may therefore fill it with EPS beads, and close it off with some steel mesh so any rodents can travel up and munch away at my EPS boards.

The slab to the right is a piled slab, so is higher than the footing. I need to keep the brickwork in situ (at least the outer leaf) to retain the compacted hardcore from spilling underneath the piled slab. Potentially I could remove the inner leaf brickwork (on the left) but the ground is all levelled and measured to the nearest 5mm.

Hi All, I previously removed an exterior brick wall in order to extend lounge. Where my new slab extension meets the old bungalow cavity wall, I need to decide what to do with the cavity that goes down to a depth of approx. 800mm to the footings before I lay down my new floor slab. The old bungalow floor has been dug up in order to install 300mm EPS with UFH in 100mm meshed concrete. The attached pic shows the new extension to the right of the cavity with sand blinded hardcore floor of bungalow to the left. My options as I see it: 1) Leave cavity as it is and just cover the cavity with 300mm EPS. 2) Fill cavity (with gravel / concrete) 3) Fill with EPS beads I have plenty of beads at my disposal, so I am tempted to go with option 3. TIA! OB

HI Nick, This was going to be my next headache, trying to understand what I would need in terms of a TS. Probably should have that decided really before I go for my final choice of UFH setup, but reckon I can delay my TS choice until later. Will need to have a family meeting to decide how many showers people intend to take when living in 'normal' conditions again to determine heat and water demands. I may come knocking on your door later!

Yes, to start off with I looked at a GSHP and cried at the cost and relative marginal improvement on an ASHP. Piled foundations then meant I had to rein in my costs so the ASHP had to go too. Wife prefers cooking with gas too. She asked me how she was going to cook with an ASHP. Same applies to my manifold situation now - I see no real benefit in having 2 rather than 1. About £400 extra to have an additional one in another location including all the extras (pump, wiring box, actuators, valves...). With one manifold, there may be more 'usage' in that solitary pump and a bit more metrage in pipework but less capital cost. I may have to replace a single pump sooner rather than having 2 pumps, but that replacement pump isn't going to cost me £400.

Had another attempt last night. Just managed to lose the flamin' background floor plan somehow.....grrrrr! Not pretty, but I can see at least see where the metrage is going. Longest loop appears to be the living room areas as expected, but the dining room circuit could extend into the lounge area. Or potentially add an extra circuit in the lounge/garden room areas. Changed my mind from ASHP to gas boiler. Potentially do that later when the house has convinced me it's good enough for an ASHP! 130m? That sounds somewhat reassuring then with my longest around 117m, unless I can get Wunda to re-look at their design. Yeah, hoping 150mm should suffice, especially with a boiler at this stage, maybe an ASHP in future.

1 pump with 2 manifolds? Didn't realise that could work with just 1 pump. Could be an option for me maybe with the pump in loft feedind both the manifolds downstairs. I have been quoted between 1000-1100m of pipe. Not passiv levels here, but should be a lot better than BRs! I don't have 12 zones. That 12-port manifold will be feeding multiple loops in a room (like the lounge/garden/dining room) but that will end up being one zone. Looks like I have 8 room stats in both quotes. Want to got for 150mm centres to be 'safe' rather than 200mm. One of them said "why not go for 100mm if it's efficiency you are after...". Can't go through the study wall, but could go through entrance hall/lounge wall to save a few metres. I did wonder whether to have a hall zone or not. The living area is a lot of glazing, so potentially needs less heat being fed there with solar gain. So on some days the hall may still feel cold in comparison to those areas, hence the need for its own zone.

After a number of UFH quotes I have ended up with 2 that I need to choose from for my 150sqm floor area. One provider (Provider “W”)has quoted from 2 manifolds (7 ports) due to the long pipe runs. The other has provided just the one 12 port manifold (Outside bedroom 4) and some of their pipe runs are just over 100m (think the allow for 105m). They have not elaborated on how they achieve this. I have attached a floor plan showing locations of manifolds (“Man 1”, “Man 2” in red ). Green areas are those depicting locations which will be offlimits to UFH (Kitchen units, toilets, built ins etc), and those in red, are further areas that won’t accept pipework (structural additions mostly). Biggest issue is the long pipe runs to sitting room/garden room if I am just using one manifold in location outside bedroom 4. That’s why provider “W” had added another manifold in entrance hallway. The additional manifold means they are £400 dearer that the other quote. Single manifold means that most of the hallway will just be feeds going off to control the kitchen/garden/sitting/dining rooms, so reducing temps in those areas will ultimately impact temps in the entrance hallway area. I don’t mind paying the additional £400 if it means a more efficient system. However, having 2 manifolds, also means two pumps to power and more parts to go wrong. “W” will have 4 loops in the garden/sitting/dining room. I suspect that the other provider may simply have put in 5 loops to keep the lengths down. “W” has essentially said this is the best they can do. I have had a play with loopcad but that’s not really helped me with any decision making. So seeing whether the experts have any real life experience here / opinions that may sway me to go for 1 vs 2 manifolds. Efficiency is what I am after, but I also don’t want to be shelling out for a new pump every few years if it’s being overworked. FYI: · 150mm pipe spacing · Pipework tied to mesh in concrete (no screed) · Boiler location in loft above dining room on rightermost wall · EWI, 3G glazing, 300mmEPS (or PIR equivalent) in most floors

Insulated too!!! very impressive! 3G window? Plenty of space in the log store for bulk buying of toilet rolls!

Fluffy towels?? Do they exist??? Tumble driers? Do they exists also? Camping in the static has meant the boss has forgotten about these 'luxuries'. And long may that continue once we move in!

Wrinkles??? Bugger, can't have that then - that's really going to affect my u-values.

All the ones I ever want on there are collection only. The other complaint I have is that they never give a spec as to what you are getting. For certain applications you need to be sure what you are going to get delivered/fitted. I'm looking for under slab insulation, so being cautious with what can go there. Not bothered about a few scrapes!. Where are you using this batch Peter?

I wunda why you all think it's Wunda that I am discussing here??? That price of £800 does not seem a bad price then. Mine is 135sqm but I don't need the floor trays (pipes cable tied to mesh) which seem to be pretty ££. But then they have quoted for two of their Grundfos pumps as well as two of their pump stations, so that could be really pushing the price up. Why no pump? What's going to circulate the water? Does your ASHP also push the water around your pipework then?? I would have though you still need a dedicated UFH pump, but I am no expert.

No pictures. Website does not seem to distinguish what they are, certainly don't sell them seperately it seems. Bit like going to the shop and asking for a bottle of lemonade "I'd like a lemonade bottle with some lemonade in there as well please". Or ensuring that the car you are buying contains an engine....

Hi all, looking at getting my UFH purchased this week once I get these last two competitive quotes sorted out. One supplier is approx £400 dearer so hopefully I can get them to stand by their slogan of "will beat competitor quotes bla bla bla....". In any case, they have itemised as separate components "grundfos EuP 22kw pump" as well as "pump station - grundfos". Are these not the same item? One is a pump and with a temp blending function and the other is what then? I'm speaking to them tomorrow to get their price knocked down a bit more hopefully but would be good to know before hand as to what they are quoting me for. I've already had to correct them on a few items, so would not be surprised if they have duplicated components here, which would explain the difference in quotes. TIA!

Thanks @JSHarris. Mine is more of a sand than a grit. It's been in jumbo bags out the front drive for a couple of years but no sign of any ants in there. Maybe they've been waiting for a warm slab to move to. That's good to hear - edge dwellers only! I did have a rat living under the cellcore EPS system in one of the extensions last year. He seems to have moved out and all holes are now concealed. Just need to make sure the squirrels don't return to the loft this year.

Just levelling off my last few rooms with sand prior to laying down my EPS/PIR boards. I remember on ebuild someone suggested to me that it wouldn't hurt to sprinkle down some ant powder with the sand. It's probably overkill, but I don't want any ants in there creating a labyrinth of tunnels that may create hollows within the insulation. FWIW, floor build up: Bamboo/tiles Meshed concrete/UFH EPS/PIR Radon barrier EPS Sand Hardcore No issues with ants in the property and removing the old slab, there was no sign of any ants, but I've read of ants making cosy homes within EPS/EPS beads (but mostly where it's been moist). So if I do use ant powder, is there anything that I should be aware of? I don't want the powder eating away at the EPS! TIA

If your glulams are 'low' enough you could create a flat ceiling either side of the beam and put ducting/wiring/ etc in there. But I like the wardobe option best in my case. I would have preferred them out of sight, but I;m sure they can be disguised.

@JohnW: Not sure whether you are retrofitting or not....I don't think you are, but I am considering using a product called "Agilia", which is described as self-levelling/self placement, so no power floating needed, less labour needed and works fine with UFH. Good for retrofit as in my case where access for power floating is not an option. But, I think you are new build, so may as well go a la JSHarris with C25(?) concrete.

Hi Lizzie, I'm looking to buy my WRC very soon as many timber merchants are now (if not already) raising their prices due to the post-Brexit world and poor Canadian dollar:GBP forex. Prices up by as much as 25-30%! So buy quick, if you can.

Hi Joseph, Digging out was a bastard (30mm screed), 100mm slab, the rest was a mix of post war rubble and clay. 3 grab lorries (had a local guy who needed quite a bit of the rubble/soil so that helped me 150mm hardcore back in (circa 12t), compacted and levelled with a 10mm tolerance. Up to this point, probably spent £3200 in man hours plus materials, tools of £500. UFH cost will be approx £1200 (will do that myself), insulation (£?) and some type of self laying/levelling concrete (£?) Some will say the payback time will be quite some time, but I work from home so I expect the heating to be on low during the day when needed.

Sorry Joseph, 'just' came across your question. Two extensions are SIPs. No new 1st floor to bungalow. Bungalow has been gutted (slab, roof tiles, some ceilings, windows, wiring, plumbing, rads).