MikeGrahamT21

Hi, Just wondering if anyone has been here before, and done anything like this. My initial plan was to use blowerproof liquid as a whole wall VCL (we have external wall insulation EPS on this part of the house, cavity wall construction with cavity filled), to stop the water vapour passing through, and getting trapped, or semi trapped at least. Its quite expensive, but seemed to do what I needed. Now they seem to have changed their advice, and say it needs a grit coat over the top of it, something like feb bond blue grit, before plastering. Thought i'd look a bit further afield, and found Everbuild BlackJack D.P.M, which is a 2 coat solution, and is suitable for application to walls as a plaster bonding agent, and throw sand on the second coat so its ready for plaster. Only problem with this is there is no vapour permeability values, I've emailed everbuild to see if they know. Obviously the everbuild product is a lot lot cheaper. Any insight would be greatly received. Regards Mike

Check IG lintels out too, even their standard lintels have a much lower PSI value than catnic if I remember right, and they're cheaper!

love the video they've done for the DryFix! Though as an addition to it, i'd be using a spirit level! Very mixed opinions on the whole foam fix, you can get fire rated versions now, like DryFix which would be best. I remember looking into it for external wall insulation, and everyone said cement based adhesive, though there were plenty of big manufacturers using foam fix, i went with cement in the end.

The more airtight the building, the better MVHR will perform without doubt. A few months back I read a university paper from Leeds Met (i think) Uni, which fitted MVHR to a number of properties and Standard Extractors to a number. They gathered information on all before they were fitted, and performed basic airtight measures on the MVHR properties (hardboard on top of floor boards, and mastic wherever possible), bringing the ACH down from around 20 to 11 or 12 ACH (so still quite high), and they performed very well, obviously fixed all of the issues with condensation, but also dramatically lowered CO2 concentrations in the air, and reduced consumption of gas for heating. So it just goes to show, that even in a building which is very leaky, they do still work. Obviously the less leaky, the more savings potential, and after installation, get a smoke pen, and work your way round sealing all the gaps, its a long hard job, and some will be more sealable than others, but you will sure make an improvement. The MVHR properties outperformed the Standard Extractor fan ones by a fair margin in terms of energy costs, and humidity/CO2 reduction.

Aluminium in its natural form is extremely hard to ignite, and melts at over 600C, so I'd say its perhaps fire rated as it is. The fire rating would likely come from intumescent (sp?) seals around the door, which you may be able to swap out yourself. If it needs a certificate for BCO though, you would be better going for an off the shelf one with cert.

PIR has a double foil face, and its not practical to put supro underneath, i'd probably be able to get it part way, but never with a proper seal, as we don't have a crawl space, theres only 2 bricks worth of room. I had a look on ebay, and managed to get a 75m2 roll of Protect BarriAir for £68, so I'm going to go down the route of VCL on the warm side to protect the timbers best I can (since the reason i'm replacing is because of woodworm infestation which we believe is no longer active, obviously caused by the timbers being too moist, though i think this was more to do with the air bricks being mostly blocked/semi blocked, which now isn't the case), and on top of where the joists are, I'm going to use 50mm butyl tape to seal the penetrations from the screws in the OSB, and be very careful that i'm 100% accurate with my screw placement!

Hi, Never seems to be a firm answer on this... We have 100mm joists with sleeper wall, which we will insulate with 100mm PIR, friction fit, and gaps filled with expanding foam. I have got some Tyvek Supro (breathable roofing felt) left over, and as its airtight to 50pa, I was going to use this across the top of the joists, before the OSB3 goes down. However I've just read online, that its more suitable to have a VCL above the joists, to stop any moist air going underneath. Ample ventilation under the floor and a decent gap. Would you say an airtight VCL may be the best option? Regards Mike

fair enough. I dropped on some Tyvek original tape other day for £13 a roll, which I thought was pretty decent, need some to finish off around the roof windows.

Wow, yeah £9 a roll is very good, I'm guessing thats not a price we can all pay? lol

If anyone is wanting breathable airtight membrane, rather than an AVCL, Tyvek Supro (i.e. Roofing Membrane), is actually airtight to 50pa (I think), so should be suitable and is reasonably cheap on ebay. http://www.dupont.co.uk/content/dam/assets/products-and-services/construction-materials/tyvek-building-envelope/Documentation/Technical-Datasheets/TDS-DuPont-Tyvek-Supro-and-Supro-Plus.pdf Resistance to penetration of air EN 12114 m³/(m² h 50Pa) - - 0,25 (Maximum) Compared with a true air barrier: Air Permeance EN 12114 0.01m3/m2/hr @50Pa Kingspan Nilvent is also classed as airtight. They all claim airtight at normal building pressures 50pa. I plan on using this under the floor boards to save me the nightmare of having to seal every little bit between the joists, and then lap up the wall, and bond to the wall itself, it'll then get covered up by plaster and skirting board.

Whats the airstop stuff like Dave? Read some bad reviews about it not sticking, as I was going to buy some for my windows.

Actually to stop this from happening, a fire retardant membrane behind should sort this out, which will kill the flames on contact, so may need a combination of both membrane and coating.

No i can appreciate that, don't think i'd want to either. Timber is going to be screwed on, so I guess i could always unscrew it to repaint if needs be.

Found this one, which seems to fit the bill. No undercoat required (undercoats seem to be the most expensive) http://www.fireproofspray.co.uk/flametect-c-wd-for-wood-clear-flame-retardant-68-p.asp And you get a certificate with it for if BC ask.

Yeah its only a single storey extension, i'll do some more research on the coatings.

Yeah 600 wide, I think the timber alone will be fine, its never going to get touched once up so it should be fine.

I'm guessing the treated timber will be hard to come by and expensive when I do. Varnish is likely the way to go with this one and re-treat and and when required. Yeah I've thought about the aesthetic appeal, which to be honest is why I want to go down this route. Timber I'm looking at is 19mm x 38mm/50mm PSE, which ends up 14mm thick, so overall probably about the same as a plasterboard and plaster, no problems room looking darker, as its got a lot of glazing anyway. Looking at a few of the treatments online, they all say effective for the lifetime of the timber, so sounds good to me

Been thinking about different finishes for the vaulted ceiling in our new extension, and I've come up with the idea of timber cladding with gaps in between (a bit like what people use on the outside of buildings), think it will look nice in there, and a little different from the usual plaster. Obviously the roof trusses are timber, and the insulation is PIR with foil face. Question is, do I need to have any sort of fire retardant barrier behind the timber cladding on a ceiling? I've seen some on the web for about £100 a roll. I'd ask building control, but I doubt they would understand the concept of not using plasterboard lol

I will indeed, thanks for your input as always. Will do!

Yeah I agree mate! I'd rather pay the extra for solid brass. Well, I think my plan is set. Just need my wife to get better now, so I can knock through into the extension and then start all of this work, so it may not happen this year, but hopefully it will, as that means shes better!

The ones I've chosen are solid brass stems with chrome coating on them, and a pushfit connector, a little more expensive but should look nicer overall, then I'll put some chrome pipe cover on the little section of copper which will be showing, or paint it with some kind of chrome paint, I'll make sure it looks good either way :-) Infact, I've even found a white one: https://www.plumbnation.co.uk/site/hep2o-spigot-elbows/ but they are plastic, i'd rather the brass one for the compression as you say

it would be good to know a realistic ball park figure without having to get a company out to do a full quote. Our main issue with a dormer though is lack of space to put stairs, we could make it work but it would be hard work, we don't have a massive amount of square meterage, though lots of houses on the estate have dormers, its often in the slightly larger version of our house, not always, but most of the time. We would have to lose the 2nd bedroom for the staircase, so would need at least 2 bedrooms upstairs, gaining us 1 extra overall, ideally we'd get 2 bedrooms and 1 shower room upstairs if we went that way. I'm up for considering anything, my main concern with dormer is whether the planning department would allow flat roof mounted solar panels, if they won't, then we are limited to a single dormer, and would have to move 8 solar panels on to the utility roof (i designed it to take these anyway, plus its south facing)

no no, it was just a wild guess, based upon odd things i've read in Magazines. I know the materials aren't that much, its the labour. House is a 2bed semi bungalow, what do you reckon rough price? This would be for a full dormer conversion, double preferably, GRP roof, with 8x mounting for solar panels (if allowed by LA), probably 4x triple glazed windows, and cedar cladding to the outside.

Yeah I totally get it, i've looked into EWI for the whole house as it stands now, and the amount it costs is crazy compared to what we would save. I did the EWI myself on an extension i built, it was straight forward enough, but really hard work, and still cost a lot of money, but less than what it would have done. Yeah I thought about it, but I don't think the savings would be enough to justify it, plus it would be nice to have extra garden! :-) I read that planning wasn't required for 2 in to 1, but was for 1 into 2, but i have no firm answer on that. OK, EPC is quite cheap i guess so thats no problems. Another thing i've just thought about, we have solar panels with FiT, would any of this affect that?

Ah right, so its not set in stone that it is required then. Its certainly possible in these houses, but it is more ££, and if we have to buy cash, there won't be a lot of ££ left to do things like expensive EWI.