Swampy

I meant trickle vents on windows, which I’d been hoping to avoid on the new windows we’ll be ordering. Do you mean something else? Yes, DMVHR units do seem to be pretty expensive.

Late coming back to this, but I’ve completely ruled out centralized MVHR now, as there’s just no way to fit it in without boxing in most of the ducting, which I don’t want to do. So the options left are to use trickle vents, DMEV or decentralized MVHR. Both these systems appear to be fairly similar, in that they use individual, smaller units distributed around the house, but DMEV doesn’t do heat recovery. I need to order windows very soon, so it’s crunch time. Anybody have any thoughts on the two systems and if one is preferable to the other? I also have concerns about how much heat we’ll lose through the units, as well as potential noise issues from outside. Thanks!

I contacted a company which sells cascading MVHR systems, but they said it's not intended for a house like ours - rather it's for apartments and small homes. So it looks like heat recovery is not going to be an option. Looking into dMEV and MEV next.

We're extending to the back, side and partially at the front, so some existing external walls are being removed and some are becoming internal walls. Knock down and rebuild was not an option, based on the fact that it's semi-detached and the build costs we were quoted for the work as it is, were exorbitant. Fortunately, we did find someone and the work is already well underway.

Thanks for the suggestions - I'll investigate further. Do they have heat recovery and they ever used in enerphit projects?

Hi, Currently in the middle of renovating and extending our 1950s semi and I need some advice on ventilation. Without going into too much detail at this point, I'm aiming to make the house very well insulated and as airtight as possible (I'm aware of the limitations of doing this in a refurb, but about 85% of external walls will be new in the end). Humidity is currently an issue in the house and with improved airtightness, I only expect that to get worse, so I was planning to install an MVHR system, however, due to ceiling height, RSJ locations and floor joist orientations, MVHR doesn't seem viable - I don't want boxed-in sections running along the ceilings all over the ground floor. I know someone who has a PIV system installed, but they confirmed what I'd read - they have a significant cold spot during the winter, where the fresh air is coming in. I'm not keen on the small, individual, 'per room' MVHR units either, as I have concerns about noise and their general heat recovery efficiency. What other options are there? I'm really struggling to find anything which will definitely work! I'm also open to getting an expert round to assess the suitability of the house for MVHR, in case I've misunderstood how the ducting could be routed, but I'm in a catch 22 situation - I have to pay for a design first, yet I won't know until after that if it's appropriate for my home (as I've said, I don't want lots of boxed in sections running across ceilings in main living areas). If anybody could recommend an MVHR installer local to east Berkshire, that would be great. Thanks.

We’re in Berkshire, but I don’t have electronic copies of the plans that I can upload.

Hi, We’re going to build an extension on a house we’re buying and have a set of plans, but we’re finding it very difficult to get a rough estimate of the cost - to make sure we can actually afford the work, before we complete on the property. we have plans, because a neighbour has done the exact work that we want to do. We will of course get our own set of plans, when/if we complete. I appreciate that build prices have increased a lot in the last couple of years, so can anyone provide a guide to cost per square meter? I’ve seen these guide values before, but what with prices going through the roof, I wondered if anyone has seen any updated figures? It’s going to be a 2 story extension to the side and half of the back of the property, plus we want to do a loft conversion (in case that’s relevant). Thanks.

So 2 courses of blockwork, with insulation in between, then rendered externally - for the new walls? Out of interest, is there any other option? We’d want to go for the maximum level of insulation, so I think we’d have to use panels (more expensive), or rockwool (thicker walls).

Hi, We’re building a large extension to a 1950s semi and since most external walls will be new, have decided to fit external insulated panels to the ‘old’ external walls which will remain as external (i.e. the exiting front wall and a small part of the rear). of course, we’ll be rendering over the panels. My question is, what are our options for the materials we use on the completely new external walls? I think we’ll probably render or clad them and we would want them insulated to the same degree as the existing walls. What are our options for the construction method and materials? That is to say, blockwork for the internal side of the cavity, then insulation, be it rockwool or panels), followed by…what? We’re looking to save money where we can, but I know that insulated panels are considerably more expensive than rockwool. Thanks!