Redbeard

Where does your rainwater go?

It does but how would you detail the 'raw' PIR perimeter on the outside - just a timber (or Alu?) fillet?

Yes, FM330 is air-tight foam.

Strictly it does not help the paint adhere to the building; it (and a bit of scrubbing) takes off any algae to which the paint would otherwise adhere, rather than to the brick. If you paint over the algae - algae falls off; paint falls off. After application of the algaecide you once more have propitious conditions for the paint to stick to the wall.

Sorry, what is the 'it' in your Q ? The algaecide?

Yes, in the wall, and no, not in every room. The idea is you put them in the wet rooms, so that the 'pull' extracting moist air from the wet rooms *pulls in* dry air via the other rooms, so yes, trickle (window or, as preferred, wall) vents in all or most 'dry' rooms.

Agreed 'get vents' but if the OP does not want them in the windows they can be elsewhere. (and see my point above).

I do fully understand that, but have spent years advising clients to design *out* the unintentional ventilation (draughts) and design *in* the intentional. Once you have vents and a couple of dMEV fans you can go mad stuffing draughts. Have a look at the Bldg Regs for the relevant cross-sectional area of ventilation you'll need. Goood luck!

See also

Strictly no, but I can give a good guess. Apply expanding form tape such as Compriband in the expansion gap. I have not come across the term 'penny-rolled' before, but assuming they use a 'standard EPDM 'detail' roller (which seems to have a min 40mm diameter) I would suggest just roll first across then up to the abutment.

Does that not depend on how air-tight the house is? It may be reasonable to assume 'not very', but AIUI PIV (Positive Input Ventilation) relies on drawing air in the loft and pushing it out through 'gaps'. No gaps, no functioning PIV?

https://www.gov.uk/guidance/appHelp! How can we avoid trickle vents on a Jacobean cottage reno?roved-document-f-volume-1-dwellings-frequently-asked-questions#can-background-ventilators-be-installed-through-a-wall-to-meet-the-part-f-requirements-instead-of-installing-trickle-ventilators-in-windows Can background ventilators be installed through a wall to meet the Part F requirements, instead of installing trickle ventilators in windows? Ventilation can be provided through any appropriate means. Installing a background ventilator through a wall that provides the equivalent areas described in Approved Document F, volume 1 can be an acceptable route to compliance. I realise your thread is entitled 'Help! How can we avoid trickle vents on a Jacobean cottage reno?' but as it goes on to talk about windows I assumed you meant 'trickle vents *in windows*. Maybe I'm wrong. Can you confirm? If you'd be happy with 'trickle' vents in walls then you don't need anyone to authorise a deviation 'cause there wouldn't be one.

Hello! I am not sure that is true. Decent (intentional, not accidental) ventilation *is* required by the Regs. Ask anyone on here with MVHR whether they have trickle vents!! You will, however, have to have some vents somewhere if not in the window frames. Search on here for decentralised mechanical extract ventilation (dMEV). I have not got chapter and verse to hand for my assertion, but if no-one comes up with it in the next few hours (I bet they will!) I will have a look for a source.

UK Gov't guidance (https://assets.publishing.service.gov.uk/media/61d727d18fa8f50594b59305/retrofit-room-in-roof-insulation-best-practice.pdf) now suggests 50mm ventilation. The resultant 125mm of PIR between rafters is not, I think, going to meet the Building Regs target of 0.16W/m2K. Rough values: 125mm PIR (to leave that 50mm vent gap): R value 5.68m2K/W approx. 'Base case' R value of uninsulated roof (if indeed you allow it any): 0.5m2K/W. Total 6.18m2K/W. 1/R = U so U value (v. approx) = 0.1618W/m2K, but this leaves no allowance for the timbers which interrupt the insyulation every (?) 400mm, so it's not 'real'. When I was doing attic room re-fits on a regular basis I used to ignore the 'base case' value and look for a depth of PIR which would give me 0.16 on its own. Of course you could simply add 25mm PIR below the rafters and you have not only cloaked your thermal bridge but, with 125mm between the rafters, you'll achieve a 'gross' U value (of course assuming 150 throughout; it's not area-weighted) of around 0.147W/m2K. A lot depends on headroom as battens and plasterboard & skim will lose you another 40mm.

Definitely +1 to @ProDave and @Iceverge's suggestions. Gets rid of most of the issue. (Doesn't, of course, alter the fact that the timber balcony will rot out in the long term, but at least with the suggested revision the timescale for both support and decking may be similar, instead of the support rotting out first).

Can we have a pic from a distance showing how the Veluxes come into the equation? What I can visualise up to now is a pitched roof 1 floor above the balcony 'collecting' water between the Veluxes and 'tipping' it down the wall. But why doesn't the gutter stop that? I am sure the answer is simple, but I cannot see it yet. More info and context = more comprehensive answers. Many thanks in advance.

Don't worry, @saveasteading, we are shot of this now, but the issue described pole-axed a sale in 2017! There had been luxuriant ivy and cotoneaster growth all over that elevation till a few years before, despite my attempts to get them removed, so they probably had something to do with it. And like you, I'd have expected some steel in the outer leaf, but believe me, it wasn't there. I do love the concept of 'Structural Chicken Wire', though! The house opposite me (in a different part of the country) appears to be similarly afflicted, judging by the droopy soldier course! (Just realised that your later Qs were probably for the OP, not for me!)

Is that the front moving or the side falling off, or both?! As per @saveasteading comment, it does appear awful.

I claim no skills whatsoever with digital pic-wrangling, but try this:

Here's the one I 'unearthed'. Big conc. lintel on the inner skin and chicken-wire on the outer, a course above the window-head. The whole estate was built like this.

@saveasteading, for clarification, my first post from further up the thread:

Perhaps I can come in on part of that one. I think I was the one who sowed the 'potentially no lintel' seed. I related a relative's situation where a whole estate of 1960s houses were built without lintels to the external skin, an issue which was not an issue until the sturdy timber windows were replaced with uPVC. I think I have somewhere the pics taken when the builder did 'exploratory' work.

Easy? We-e-e-ll, brick removal is not difficult... If it were me I'd prop temporarily (actually probably quite difficult as there appears (again, AFAICS from the pics) to be a tiny reveal, so not much to 'get hold of') and remove a couple of bricks. In reality you may probably be able to remove 2 bricks without propping, but I am not going to recommend that on a house I have never seen, you'll appreciate). If you are better than me at 'reading' boroscope pics you could just drill a hole to look. Edit: Ahah! @iceverge was posting while I typed, and suggesting just that)

AFAICS that pic is upside down (the white moulding at the bottom appears to protrude, and the earlier pics show no top drip detail, so I think it's maybe the cill, upside-down), so maybe some of the cracks are down towards the ground (re @Nickfromwales' point). Nevertheless, if we 'park' any cracks below the window for now, can I raise a further possibility? That it is not so much a problem with the lintel, but that *there may not be a lintel*. I had this problem with a relative's house, and it was the same for (I believe) many (tens of?) thousands of 1960's and possibly '70's and '80's houses. In my relative's case the house was built with reasonably stout timber windows, the top rail of which acted as a lintel. That situation pertained perfectly until the timber windows were replaced with uPVC (and at that time many uPVC windows did not have much, if any, steel reinforcement). Then the step-crack appeared, slowly, over a number of years. On sale of the house the issue was raised and invasive work carried out to prove the 'diagnosis': no lintel on the outer skin, and no, the inner-skin lintel did not cross the cavity and 'pick up' the back edge of the outer skin, as one builder had suggested would be the case. As I type now I can look out of the window to a 1960's or 1970's house with visibly 'drooping' uPVC FF windows. I have been waiting for a number of years (and still am!) for the DGU to 'explode' when finally the weight of the masonry above comes fully onto the glass, not (as I suspect is the case still) onto an air-gap above the glass.

Only that I don't understand what 'the blanks' are in Should 'blanks' be 'blocks'? And since you feel that the bubble membrane should be OK for air-tightness are you simply asking how you make the joist ends airtight? If so the best you can do, probably, is to tape them into the membrane, with either a/t tape or the butyl tape which you probably bought from Delta. (Of course you still don't necessarily know what any residual moisture will be doing to the joist ends - if they are behind the membrane - I'm not sure because you say 'on top of the ...?blocks/?blanks'). If I have misunderstood please let me know and explain how I have misunderstood, and I'll comment further.