SimonD

Brilliant. I'm always amazed when I see stuff like this and have to ask, who on earth found this out and how? ?

So many of us on here go through this, it seems to be a right of passage for a proper self-builder. In case it's any consolation at all, I'm also probably a year behind, I gave up one of my businesses to do the build myself and last week after paying my latest credit card bill realised we have about £300 left of our total budget (and yes, that's the correct number of zeros). Knew it was tight when we started and I'd hoped to at least get the heating system and temporary electrics moved to permanent and sorted before running out of money, but will now have to save for those. I can't start up the business again as it would take at least 18 months to see any real income. My builder is rubbish too as he's sat drinking tea, writing rubbish on here right now when he should be doing something useful in solitude on the site - yes, everything moves slowly here ? Sanity and health must prevail, so really do try to relax into the process, have a drink and know it'll all seem worth it when it's done! ?

Have you considered cork floor underlay? This is available in mm steps from 2 - 10mm in rolls. You can see these at spduk.co.uk. I recently bought 100m2 of the stuff from corkfloor.co.uk at a great price but you'd need to speak to them on the phone for thicker than 2mm rolls.

I spoke to a local surveyor and asked him to look at the property and review the insurer's report. He came back to me with a view regarding required remedial work plus a ballpark figure - it was complex due to banking on the side where there was subsidence meaning deep piles. I then assessed the rest of the site, for example poor access and neighbour close by whose garden we'd have to use for some of the work. Added my contingency and offered 200k below asking price. It's definitely worth getting it looked at by someone with relevant knowledge and experience.

As @nod suggests, I'd wait for the Structural Design first because you'll need to know if this requires any design revisions. I found it's also important in that it helps to hang the build together so you know more about how it's going to be built. I know there have been plenty of times I've felt overwhelmed with the number of things I've got to detail, make decisions on and finalise, but often it can be helpful to try and break things down a bit and then deal with one thing at a time only. Are you able to put together a list of what you need to do and by when for the full technical drawings and which decisions are actually down to you and not the architect, SE etc?

Honestly, if there are signs of subsidence then you're potentially walking into a money pit. When I was looking, I found the most amazing property with just stunning views. The only problem was that it was being sold following an insurance assessment re subsidence. The so called engineers report from the insurance stated it was settlement, but our surveyor said the report was useless. The risk was too great that we would sink so much money into the ground without anyone seeing it that I took that risk off my offer. The seller didn't accept so we walked. Sometimes it's just better to walk away from something despite the emotional investment. If you're feeling like this now, just wait until you're committed with your money and a problematic development and then the stress will really hit you.

Sounds like you're making progress. How come?

Studies in Sweden back in the mid 2000s found that new build airtightness reduced in the first year simply due to settlement of the building and materials. It was proposed that airtightnes tests should be carried out something lie 12 months after construction as this would be more accurate. And this is from a country that has far higher building standards than your UK developer. I think this thread is giving the green plastic a bad rap because that's where the moisture is being found. Simply removing this yet using an impervious insulation material behind the plaster isn't going to fix that at all so I'm not sure why it's even being suggested as a better way to build to avoid this. I agree. The problems as I see them are to do how we build wall systems with impervious materials and fail to ventilate properly - a recent government study found that the majority of new builds did not even meet building regs for ventilation requirements. I'm also still surprised the option of moisture open wall systems almost never enters into discussion.

Clay ground and 400mm to 1m existing foundations does not necessarily preclude second floor extention, but does require the right designer and structural engineer. Solutions can include making the 2nd floor loads less than existing, especially if existing has concrete roof tiles, pad foundations to support point loads, ring beam around existing ground floor walls. I know this because my project uses all of these things and we've got 300mm foundations in places, and that's 300mm below dpc which is 150mm above ground level. How many trial pits/trenches have been dug to obtain information? In ours too few so poor assumptions were made until I insisted on digging and investigating more. When was the original house built?

How heavy are the windows and the bifolds? This will dictate what kind of suction lifters to buy and then don't buy cheapo ones, buy ones that are clearly specified for a particular weight. If you're lifting expensive and heavy windows it's also a really good idea to have a suction guage and certificated lifter so you know it's on properly. I've had a non-gauge one let go while moving a window around and thankfully it was still suspended on a proper gauged one at the time so the window just swung around a bit. In terms of specific products, I've got a couple of Faithfull triple pad lifters, Faithful 2 pad lifters and a Grabo. I've used the Grabo a lot as it works on everything from windows to paving slabs and more.

I've had some cheap Chinese hardwood ply that was full of voids. Possibly okay for basic sheathing purposes, but not nice to work with. I was also at a merchants recently to buy a particular grade of ply. When I checked, the product they wanted to sell me only had 6 plys and obvious voids whereas the product I was asking for had 7 plys and much less visible voids. They even had another pallet of the 7 ply stuff but refused to open it for me and refused to accept it was a different product. So off I went and spent my money elsewhere...

Looking at your drawings, they correctly specify the use of WBP Plywood as the substrate for the standing seam roof. If you do decide to go ahead, make sure your tf builder complies with this specification and doesn't use osb. The spec on the drawings is correct for the standing seam with a ventilated cold roof. As it's a change of material, you may be correct in that it might require an amendment to the planning approval - are there any conditions? You will notice the difference between standing seam and whatever the lookalike version is called, especially if you're looking down on it from a window above. Best thing as always is to see if you can look at some local installations to make a comparison and therefore more informed personal decision. Yeah, a big difference there! ?

+ 1 to airtightness tape or similar. For masonry to other materials I've recently become a fan of the Soudatight LQ liquid membrane that also uses a goetextile tape to seal larger gaps.

Compared to Greencoat PLX, a single ply standing seam effect roof will look cheap and fake. I also suspect it won't come with a 50 year functional guarantee that you get from Greencoat, with a much longer potential life span if it's then maintained. I suspect your builder is just reflecting a lack of experience with standing seam and going with something that seems easier - easier for him - rather than for the overall benefit of your house. With a 13 degree pitch, there is no problem at all with penetrations within the standing seam. Yes, they take a bit of time, but nothing to phase an experience standing seam installer. Before making a decision, go and have a look a the fake standing seam solution and then go and have a look at some proper real installatios and then make up your mind. Hold up a little bit here. While osb is okay, the preference for a metal standing seam roof is 1 sarking, 2 plywood. Sarking provides better ventilation to the back of the steel roof, plywood for convenience and good nail pull out resistance for the fixings. OSB does not have great pull out resistance for the nails used by your traditional metal roofing contractor, and screws are much preferred. This adds to time and cost. At the moment, you can get plywood for pretty much the same price as the osb. Talk to you roofing contractor before the tf supplier completes this part of the build. Also double check the roof buildup. Is it a cold roof with ventilation between insulation and final osb or is it a warm roof? Again, if it's warm, make sure you get your roofing contractor in asap to ensure it's all detailed correctly. I don't think either of these statements are true re traditional standing seam roof. A recent discussion here on BH re rooflights installed in a non standing seam metal roof attests to this. Also, a traditional standing seam roof installed well will outlast most if not all the non-standing seam roofs on the market and with completely hidden fixings you're never going to have a weakness of deteriorating screw fixings, which is pretty much guaranteed and well known. Oil canning effect can be due to several issues, but you can reduce this risk by using narrower seam and other methods, but on most installs by a good contractor, this isn't a problem.

First thing I would question is the lack of ventilation in the cavity between existing wall and new timber frame. Who has designed this and what is their justification for this? You're going to have to be very careful about detailing the inner wall and any floor/wall/ceiling junctions correctly for airtightness/vapour control. If the cavity has no ventilation there is risk that moisture levels reach undesirable levels, which could result in mould growth. Ventilation is your friend here. I don't think it matters whether you use osb or ply. It can be easy to assume from this thread that all ply is the same. It isn't. A decent quality sheathing plywood will be fine for the life of the building. The problem is that there is some real rubbish out there supplied from builders merchants that don't have a clue about the timber they're selling and people want cheap, cheap, cheap. Any timber product, including osb will deteriorated if moisture levels are too high. My suspicion re the mould in the OP is that there has been condensation on the plywood due to natural humidity fluctuations and this has fed natural sugars in the timber, plus there have been some spores from old furniture that have added to the problem. Once the moisture levels in the building settle down and the sugars in the wood have been consumed there will be no more growth. If your SE has designed the TF with sheathing, then yes. But basically all timber frames need some form of racking resistance. This is supplied using either diagonal studs at required intervals within the frame, or you use plywood/osb.

Thanks @nod, yes priced is preferrable. I'm just trying the get a ballpark so I can assess how reasonably the overall price is, although it's going to be a multi visit job with a few hours of 1st fix and then 2nd fix work.

Given that they're like hens teeth right now, what's the going (reasonable) hourly rate to expect for plumbers in South West/ Bristol kind of region?

The Diathonite they used looks like an amazing product, but does it half cost, especially at 60-80mm thickness.

I know. After reading that other thread, I just couldn't help taking the wee ?? My sincere apologies, I'll close the door on my way out ? You're welcome. Yes there is something strange about sitting there all warm and then if you wave your arms about, they get cold.

Yes, I just started reading the above linked thread, then lost the will to live with another one of those BH threads...? ?. I've been using a IR panel heater in the garden office for nearly 4 years and it works really well for that purpose. I currently also have 2 IR heaters in the house heating the top floor. The house is unfinished and it's a temporary solution until I get our heating system installed and up and running. However, my experience of it has been interesting. I currently have 2 1.3kW IR heaters which heat the whole space more effectively than 2 2.2kW fan heaters (total usable floor space is over 86sqm with ceiling heights up to 3.6m so not a small space). They provide more comfort in the space, especially when you sit under one as it's like sitting in front of a nice fire. The heaters do end up heating the whole space although it takes longer to reach temperature and the space outside of the heat zone is experienced as cooler (e.g they will get the whole space temperature up to 18.5 when outside temp is 0 or less over a few hours and this is with completely unheated ground floor). As the heaters do have some effect on the body of the building there is some residual warmth/warming after they're turned off. I really like sitting in their heat zone, they do work fairly well, but would I choose this as a whole house, permanent solution? No. I would possible choose the odd panel in selective positions in the living room for when my mother in law visits when the house is complete and wants that fireside comfort. I'm sure they're unquestionably 100% efficient somewhere but unquestionably 100% at what I'll leave for others to debate somewhere else ?

The easily accessible ones written for more public consumption tend to be but there are a lot of decent non-product specific studies in the more academic and building physics resources of you can get to it. Mould and bacteria will eventually grow on pretty much anything, given the right condition won't it? I think it mostly about ensuring you build in a way that doesn't provide these conditions rather than rely on a single specific material or solution. I learnt more about the behaviour of hygroscopic materials etc. through the study of ventilation than the study of the specific materials themselves. Not long ago there was a government study that found that the majority of new builds don't even meet minimum building regs for ventilation. Hence why I think we'll soon be seeing mechanical ventilation in homes mandated, but we'll have to see whether builders can even do that right.

There are plenty of studies to understand this, but it would require a veritable tome, but in brief: If you have a wall built using waterproof principles such that it is designed not to absord or allow ingress of moisture then any and all moisture released into the building requires removal entirely through ventilation (regardless of the means of ventilation). With a moisture open wall, the materials in the wall can absorb peak loads of moisture released into the building and then slowly release than moisture back into the atmosphere. It's works similarly to decrement delay in insulation and has the effect that it flattens the relative humidity curve within the house. If the entire wall buildup uses moisture open materials, the pore structure will allow the moisture to travel through the entire wall structure too. From studies it has been found that hygroscopic buildups can reduce relative humidity within the building by as much as 25%, which will obviously reduce risks of mould formation. Not only that, it reduces total ventilation requirements, the capacity of which is typicaly designed in order to remove moisture from the building. The other side to it is that materials like lime plaster inhibit the growth of mould and bacteria.

It's because you're dealing with a wall that's been there for 140 years and is built with different materials that deal differently with moisture. Hence why you can't just supplement a partial newbuild wall buildup onto this existing wall. Remember, your full fill cavity batt wall buildup will still need a cavity tray and means to direct any collected moisture out of the cavity - this would cleary be problematic, as you've found, with your existing wall where the moisture has nowhere to go should it collect on the inside. This is quite likely given the complexities of detailing vapour control within such a retrofit project. This is where capillary open materials work well because they effectively absord this moisture and pass it through their structure to a dryer atmosphere. Okay, so the wall has been exposed to the elements for its entire life and may potentially have gone through many freeze/thaw cycles already. Maybe this isn't therefore an issue in your particular case, but it is relevant to anyone else looking to do a retrofit in an existing solid wall house (which is totally relevant to the op). The salts have potentially accumulated with the wall for its lifetime due to the buildings historical use but either way it's currently speculation and due to experience better to assume the presence of the salts rather than not. In your particular case, however, it's important to consider how your conversion project is going to change the environmental conditions for the walls as you're going to be adding both heat and moisture, and vapour pressure etc. to a wall that has not ever been subjected to this. Therefore, understanding and considering things like interstitial condensation risks and moisture transport within and through those walls in light of the new conditions is essential.

Amazing project by the way. Love the building and what you're trying to do. I'm rather jealous (or is that just Stockholm syndrome from difficult projects?). Anyway, yes there are varied views and this is partly because we still don't fully understand the hygrothermal nature of buildings. However, there is a certain consensus building, especially with regards to retrofit in older buildings which is evidence based as opposed to firmly held views. I think the situation is improving from where it was even 5 years ago. Generally, it does seem to be falling on the side of moisture open materials to reduce risks. I'm with you on much of this although I'd say the one thing missing is salts and their effect on moisture within the walls. Your 1 st meter or so of dampness is likely to contain quite a bit which will soak up more moisture and delay its drying out, but with also add to the amplitude of damp/dry cycles. Some of this is evidence based, some of it isn't. I think there is a fair wind blowing in the direction of the principle of not to tank the inside of the wall with imperveous materials on an old building such as yours. When you speak of bringing damp outside air in and encouraging evaporation to the warmer void which would otherwise permeate outwards does not follow the typical laws of vapour pressure in buildings. Typically, although not exclusively or always, a house will have a higher vapour pressure to the inside than to the outside. This typically means that the moisture will travel outwards where the air is for the most part dryer. So whilst the wall may be able to dry to the inside, this vapour will travel towards the outside, by whichever means of least resistance - this may be through the walls, or through the ventilated cavity, or even a window. I'd like to clarify, just in case it's needed, that I'm not suggesting your solution is wrong. I'm merely pointing out that there may be problematic details in what you're proposing that unecessarily add risk to your solution when it comes to moisture. For me the consensus is pretty clear. You either go for a solution that is attached directly to the wall and takes the form of a moisture open (vapour and capillary open material),, if suitable on your wall depending on its dampness, or you go for a separate inner leaf which provides a ventilation cavity, which may use a vcl, or maybe not. I do hope they're of assistance because I know what a pain this process can be. An inner timber structure could very well work, and as I said, I'm not dissuading you from this. The question is more what the correct detail needs to be for the buildup. It's because we're talking a completely different context. To quote another source (link below): Link: https://historicengland.org.uk/images-books/publications/eehb-insulating-solid-walls/heag081-solid-walls/ Another link is re solid wall insulation is Scotland but a bit more out of date: https://www.changeworks.org.uk/sites/default/files/Solid_Wall_Insulation_in_Scotland.pdf Do not confuse modern new buildups with what might work on a historic building - that's what has caused so much historical damage in the first place. This is from one of the referenced sources of the current government best practice guidance I linked to. If you read the document I link to above from Scotland, a similar point is mentioned: that in some circumstances using thinner IWI is better due to the problems associated with cold bridgig etc. so more insulation becomes counter productive. Given the value you can get from your existing 600mm walls, have you looked at using a moisture open solution that could go directly on the wall? This to me seems like an ideal candidate, at least worthy of serious consideration as it seems to mitigate many of the issues you face with having an internal stud wall IWI. It is also supported by a sigificant volume of current guidance. I appreciate this is different from @Gus Potter's excellent suggestion, and think it would be worthwhile exploring detailed buildups with each system to compare the various costs, complexities, outcome and viability of each side by side. There is also the slightly crazy option of leaving the wall uninsulated for now until the walls dry out and then consider your options further down the road.

Yes, we've had that too! They even left their work clothes in bags in the house when they went home. Stank the place to high heaven and brought one of my son's to tears. I said my goodbyes asap and thanked them for their hard work. That was awful! And sorry I can't add any value re the kitchens. I gave up and am making my own...