Redbeard

Makes one think of the oft-expunged verse of 'All things bright and beautiful'! It's about balance of power.

A Green Building expert gave me a useful rule of thumb re 'hybrid Warm Roofs' (a Warm Roof being one which has all the insulation above the rafters). He suggests a condensation risk analysis for a 'some between and some on top' lay-up, but offered a quick possible alternative, which is that the insulation on the top of the rafters should have at least two-thirds of the R value, with the insulation between the rafters having a third. That reduces significantly the risk of interstitial condensation at the interface. Your '190 between and 40 on top' would not meet that rule of thumb. I realise that there are different approaches with fully-breathable materials (full-fill Warmcel, for example) and I think I may have heard of one of the wood-fibre providers endorsing a lay-up such as you suggest, but it's worth checking with your supplier. A quick calc says 230 of flexi WF with a lambda of 0.039W/mK (Pavaflex, for example) would have a gross U val of nearly 1.7W/m2K *making no allowance for the thermal bridging of the rafters, which will make the adjusted U value worse still. I thinnk Gutex's 'flexi' maybe has a lambda of 0.036W/mK, which would give you a U value of 0.156W/m2K at 230, but again, unadjusted. I can't really answer re the roof height increase. Most importantly, is it detached? The neighbours/planners may not care or notice, or they may. Sorry, I don't knpow, but I am sure others will be along.

A bit late for this info, but: "Is planning permission required for new or replacement driveways? Planning permission is not required for a new or replacement driveway of any size if it uses permeable (or porous) surfacing such as gravel, permeable concrete block paving or porous asphalt, or if the rainwater is directed to a lawn or border to drain naturally. The government's Guidance on the permeable surfacing of front gardens (PDF) explains the different type of permeable surfaces available and contains guidance on the design and construction of permeable driveways. If the surface to be covered is more than five square metres, planning permission will be required for laying traditional, impermeable driveways that do not provide for the water to run to a permeable area. This is in order to reduce the impact of this type of development on flooding and on pollution of watercourses. Please note that these permitted development rights do not apply to flats, maisonettes or houses that have been created through change of use permitted development rights." https://www.bradford.gov.uk/planning-and-building-control/planning-application-and-building-regulations-advice/paving-front-gardens/#:~:text=Is planning permission required for,of use permitted development rights.

Option 3. Do most of the garage fill with EPS, depending on relative cost of conc vs EPS.

Ah, so I read it as: The 'retained side' means the buried bit. So if you are looking at the finished retaining wall from the lower side you will see no strengthening pillars. Any vertical reinforcement required (rather than strengthening via - possibly stepped - thickness alone) will be buried behind the soil retained. That's how I'd understand that, but IANASE!

I realise this post is in the context of EPS-clad blocks, but a reminder that XPS also leaches the plasticisers out of cable sheathing. I was once puzzled as to why I could not move a 2400 x 600 sheet of XPS I found in a loft void. It came up a little but would not 'let go of' something. Found it had 'glued' itself to a series of lighting cables!

Can you? You'd probably need to ask your sol'r since, by doing so, you would be fettering their 'funding stream'. What about water disposal? What are the drainage arrangements? Are they seeking to get you to pay +30% on top of disposal as well as supply? (Or is drainage private?). Arguably it's a sound decision *not* to, for them, insofar as they can charge you if you don't do them. Or have I understood this wrong?

I am not yet engaged with AI except as a method of speeding up meat production, but here's what it says: "Generally, upgrading room-in-roof insulation does require Building Control approval if more than 25% of the roof area is being replaced or re-covered, as this triggers the need to meet current thermal insulation standards. If the work involves replacing or significantly upgrading a thermal element (like a roof), building regulations apply, and you'll need to ensure the insulation meets the required standards. " ..and that's the line I have followed. Bldg Regs defines 'renovation of a thermal element' as 'adding or replacing a layer' (of an 'insulation sandwich')

You have already answered your own question. XPS (I assume) was spec'd so that it would not become a wet sponge if flooding happened again. It has not been used. A dry sponge has, and a dry sponge will get wet in a flood. Obviously tricky as you say most of it is completed, but you did not fail to follow the spec.

If the specification of closed-cell material (XPS, I kind of hope, but OTOH it floats well) was specifically related to knowledge of the flood incident(s?) then it arguably matters a lot. If the builder had the specification it is also arguably their problem. If you expect (at least the possibility of) flooding again then yes, the use of a material which sucks is an issue.

Re my post: should read 'ask for *their* comments'

Have you notified the owners (presumably the local authority, with no budget for such works) that the lack of adequate drainage on their property is causing a periodic nuisance and asked for this comments?

Ow! So sorry to hear that. Hopefully someone on here can suggest a suitable person. Perhaps a minor issue, and perhaps most people will be VAT registered (I never was, and equally never was a 'window person'), but Deceuninck could have ruled out an excellent non-VAT-reg'd specialist there.

I guessed 'Micro-dumper' - and at least one variant is referred to as that. (https://www.cjhire.co.uk/product/industrial/hi-tip-narrow-dumpers/micro-dumper-2/) (No connection with that firm; just my first search result).

That's RD SAP for you! Vague data in; vague data out, plus the way in which EPC assessment was marketed as a money-making opportunity - 'Full-time wages for part-time work' was one of the mantras at the time. I did not believe it because I had seen a similar set of circumstances with (inland waterways) Boat Safety Examiners. A race to the bottom in terms of price and quality. There are still many EPC assessors who want to do a thorough job, but the early (and probably continuing - I don't know) over-supply of assessors meant that prices were forced down to a ridiculously low level. You are right about not liking (and I would add 'not being able to recognise') real construction. I wrote to the certification body of one assessor who did not recognise EWI in spite of all the 'clues'. I told them I was baffled. 'So are we'! They explained that they give all the necessary info in the training, and offer a help-line in case of doubt. To be fair you probably don't have to be a building professional to be a good EPC assessor, but you do have to have, or develop during your training, a proper *understanding* of buildings and of what may have been done to them during their lives, so that you can make an intelligent 'stab' at what is 'beneath the skin'

Are we at cross-purposes? I am talking about insulation in roof voids, on the flat, not walls.

@Pocster, could you post a cross-section of the attic room and the voids surrounding it? If there is, for example, an apex void and reasonably-sized eaves voids it might just be possible to stuff but not too (tight!) them ridiculously full of mineral wool (500-600mm?!) so as to get a weighted average of 0.16W/m2K.

Hang on, it's a long time since I dealt with rentals but does renewal of an HMO licence *really* allow them to move the goalposts every term (how long is the term)? And a Q - Is the '100mm assumed in the roof' PIR or mineral wool? And are there both sloping and flat ceilings? I assume so. No sweat (or not much) to upgrade 'fluff' in a void. More so to insulate sloping soffits, but it can be done. 150 PIR will give you 0.16 or slightly better. BUT I cannot, in a quick search, find anything on the web saying that they can require an upgrade to current standards. Of course I may be missing something. If we ignore the 'base case' R value of a roof (SAP assumption for uninsulated is U value 2.0W/m2K, therefore R uninsulated is 0.5M2K/W), taking the view that thermal bridging of rafters etc may more- or-less cancel that out, then 100mm of mineral wool (with lambda value 0.044W/mK would give a U value of 0.44W/m2K, a long way from 0.16. However if it is PIR it's 0.22W/mK, not so far from 0.16. And yes, they do mean minimum!

What U value have you been quoted for the floor? Is the Perimeter/Area ratio fairly low?

I should have said 'welcome' before I went ahead and answered your other Q. So belatedly, 'Welcome!'. All the answers are here. You just have to know the questions. How old is the house?

Your 1st point possibly suggests to me that the external ground levels are no longer where they used to be, and possibly that the ground surface is *harder* than it used to be, allowing more splash-up. Many many houses have no dpc and no significant damp issues. Your title suggests you *do* have damp probs, but can you give us more detail?. My own experience with inserting a dpc is it is a hell of a lot harder than you think (I thought) it was going to be. A lot can depend on the depth of mortar joints. I am absolutely convinced that a huge number of the injected dpcs one sees were never necessary in the first place. The attitude of many Building Societies and public sector lenders/grant-givers, in the 1980s particularly, led to (I would guess) hundreds of thousands of installations of injected dpcs in buildings which were not damp. More context please Incl. pics of possible, and we can get more specific.

If you decide to retain the pipe and do a soakaway then (a) you have to establish whether your ground conditions are conducive, via a test pit, (lots on here IIRC) and (b) you need to be 5m from buildings and xm from boundaries. (I have used 'x' because I have seen 2m, 2.5m and 'If you are close to boundaries you should discuss this with your neighbour.' - Surrey Bldg Control Guidance note). BUT, as mentioned in previous replies, we need to know what the problem was. Did the gutters overflow regularly? Did the neighbour have an unwanted 'pond'. Where does their 'proper' fall-pipe terminate? In a drain, a soakaway, 'nowhere'? It's an odd situation and certainly one to feel uncomfortable with.

I always think of wall-plates as sitting on top of the masonry, but I assume you mean that 'low purlin' as the wall-plate? I cannot see what goes on below the wall-plate/purlin, but there appears to be light coming in -- ?? Assuming the roof continues down in an oversail then why not bring the hempcrete up and over the top of the wall and physically fix it to the back of the VCL? Ahhh.... because you cannot get in there to fix to it. I was thinking of a 50/50 mesh/air-tight tape 'combo', the mesh 'plastered in' to the hempcrete and the tape stuck to the membrane. Goes off to think for the evening....

Have not looked at crate prices recently but it will be worth a comparison, or do you have some vehicular loading issue?

I think if I had been your architect (which I never would be as I am not one!) I might have played with the levels of the majority of the flat roof so that , without diminution of the insulation, I could get a channel in hard against the parapet with the outlets, with a slight fall each way from the middle. The fact that you have chosen GRP makes that easier than with any other covering I can think of. And Robert is your Mother's brother.