epsilonGreedy

@CalvinHobbesthe main factors for the thermal performance of your new build are: Wall Insulation Attic insulation Floor insulation Glazing thermal performance Air tightness MVHR Heating system Natural solar gain Solar panels Apart from item-1, these factors are independent of your timberframe or not choice. In the case of masonry walls a wide cavity will get you a decent thermal U value. I have read many of these timber frame debates over recent years here and concluded the best argument for timber frame is that it simplifies project management because you would contract out the creation of a weather tight shell to an expert contractor. The erection of the shell happens in a blink of the eye relative to the rest of your self build. Current material price instability is particularly acute for wood which is a transient negative for timber frame.

I am glad someone else posted this. Recent electricity price gyrations seem to have tilted the decision back in favour of mains gas for the moment.

A mechanical mortar gun which works like a giant mortar syringe is one possibility, trouble is these require a wet mix and the whole job becomes messy. The other option is to us a thin pointing trowel but this is a fiddly job on the vertical perps. With my brickie team this was a 2-stage job. First is the usual extra 3 seconds a block to butter the end with mortar then the brickie's mate went around pointing up both sides of the block wall within the hour and filled in any voids. The cavity had a rougher finish but was still better than your example.

I have watched the ufh pipe installation at a neighbour's house and concluded intricate layout plans are a bit theoretical when it comes to fixing down the pipe from the reel. The plastic pipe seems to have its own idea where it should go.

Until reading this thread I was planning to omit ufh pipes below fixed kitchen units. I still think the idea has merit where the counter top is along the boundary of the room. Given the 600mm depth of a counter and the need for pipes at say 200mm for an even floor temp, this suggest a useful temperature gradient under fixed kitchen units when no pipes are present. Skipping ufh pipes under an island is another matter.

I see a danger here, last year the price of crude oil in the US went negative because there was no demand for futures as they expired and became deliverable. Owners of these contracts had to pay others to store the unsaleable commodity. In an extreme case the forum could design @SteamyTeaa barrage balloon so he could take delivery of his excess methane.

Did it fall due to general rotting in the eaves? Just saying.

Why design for a higher target temp in the kitchen than the living room? I would want the reverse. The layout pipe patterns are far too fussy, any UFH installer will laugh at your diagrams and run the pipes in simple repeating patterns.

I suspect the stairs will need a longer run to reach 1st floor height. How high are your ceilings. Are you building new or doing a conversion? If new build I suggest it is difficult to break even self building an ordinary small (1100? sq ft) house without lots of hands-on graft.

Daft question. When integrating insulation at the point where cavity wall insulation batts meet horizontal loft roll insulation near the wall plate are they ok meshed together? I have lots of cavity batt insulation offcuts spare that would be ideal to bridge between the wall cavity, up over the wall plate and then say another 200mm into the attic. For context and diagrams see this thread

Ok interesting you were a roofing pro I recall. Just one matter concerns me if going even thicker than 40mm. At 40mm in the smaller roof I will only have 150 - 25 (airgap) - 40(PIR) = 90mm above the wall plate. I think I will need a continuous section of insulation roll stretching from the cavity up under the PIR at the wallplate and further into the attic space. If just bundle a section of insulation on top of the cavity and upto the wall plate but not through into the attic it might just flop out over time and drop into the boxed eave. Is this a real concern?

Thanks, in the absence of any advice I would have guessed 40mm or maybe 30mm was strong enough for a 10" span though I have never handled or cut the stuff before. Plenty of threads here on the subject of cutting PIR I recall. I take your point about holding it in position as I don't wont the PIR sections sliding out of place during a gale because it would be a pain to reach the wall plate from inside the loft with 350mm of insulation down and a 30 degree pitch. It is surprising how far back the PIR (or rafter roll) has to come to remain above 350mm of loft insulation given a 30 degree pitch. I was going to use a slimmer batten cross section to create the slot to hold the PIR, was thinking one size down, maybe 18mm x 38mm? Ok I feel happier with Plan-B because I could imagine the loft space getting damp near the wall plate if water pooled on the membrane and leaked through slowly. I think it would make sense to fit some loft insulation roll before closing up the eaves and fitting these PIR spacer panels.

Ok thanks for the warning, Plan-B is to ditch the rafter roll and use cut sections of PIR as a spacer between the rafters to achieve the same ventilation airgap. That diagram above illustrates the limited height for loft insulation roll at the wall plate with a 30 degree pitch.

Possibly. I thought Torx was a cross manufacturer design and Spax had enhanced it with an extra lug on the bit head? I could be wrong.

I thought your new build plans had stalled but it reads as though you are watertight now?

One gotcha that I encountered in the past was a rural property with a nice plot, however most of the back garden was still classified as arable land from a planning perspective. The official ornamental back garden was tiny which might have hindered building an extension. I suggest sounding out your local planning department to assess what is permissible before advancing with detailed plans.

I hope this extra drawing illustrates where the PIR will be fitted. I am referring to the part "spacer maintains 25mm clear airway".

I was planning to use flexible rafter roll to create ventilation channels to promote air circulation from the eaves to over the top of the loft insulation rolls in my cold attic space. However the Manthrope fitting instructions warn that the loft insulation should not be pushed tightly into the gap between the wall plate and rafter roll. I assume there is risk that the loft insulation will push up against the roof breather membrane and obstruct any water dribbles flowing down the gradient of the drape between rafters. My roof has a 30 degree pitch and in on section of roof the slender rafters result in a height above plate of just 150mm. This increases the risk of an upwards bulge in the membrane. So I am going to change the design and fit rigid PIR sheet between the rafters instead of rafter roll. The rafters are at 300mm and 400mm centers. What thickness of PIR sheet should I buy that will be strong enough not to buckle in the event that loft insulation is stuffed with excess force to push it down to the eaves? In practice I will try to fit some loft insulation roll to create a snug fit down to the cavity closure before the PIR panels, membrane and roofing battens are fitted. I anticipate most inter rafter sections of PIR will be 265mm x 800mm slotted into a groove formed by slim wood battens top and bottom.

I tried to simplify matters by only using Spax head screws. Now I am looking at the Screwfix site thinking full thread or partial. Yellow coated, zinc coated or proper stainless steel for the inside of a wooden boxed eave and that is before considering size.

Think you are right, I suffered a brain malfunction. The 4x50 screws are for fixing the 20mm fascia onto the reinforced rafter tails, I am on 300 centres and so hope the cast aluminium heritage guttering won't stress the fascia fixing. I have some 5x60 to hand but I don't like driving such a fat screw into a relatively small lump of wood as used on the rafter tail reinforcement. I will get some 4x60 ordered. So far I only used stainless wood screws, would a real pro be ok with the yellow wood screws on a non exterior facing job inside a boxed eave? https://www.screwfix.com/p/spax-yellox-pz-countersunk-woodscrews-4-x-60mm-200-pack/61066 Ok off to do some destructive testing.

This sounds interesting but is there typo or spell correction error in that quote? CO2 ppm is a global atmospheric measure. Yes I watched a Horizon type program 20 years ago warning that if the volcano slips into the sea a tsunami will roll over the Bahamas and inundate the US east coast. They have a role to play but most analysis suggests volcanoes can result in a climatic wobble of a few years until the atmosphere clears out the high altitude dust. Your lifestyle and probably your life is most at risk from the next Carrington Event which is overdue.

99% of humans and 105% of scientists agree that the world is going to end in 3 or 12 years in a red hot fiery conflagration unless the CO2 level stops climbing, therefore I conclude an ice-age is not an immediate threat.

Is there a general formula for choosing the right sized screw assuming softwood and a countersunk head? I am hoping someone will offer a formula like: "not less than 2/3rd of the screw length in the larger piece of wood" "always screw through the thinner piece of wood into the thicker" "Screw diameter should not me more than 5% of the thinnest piece of wood being jointed". For example I am currently adding blocks to rafter tails so that I am not fixing a wooden fascia into the end grain of the rafter tails. The rafters and supplementary blocks are both 38mm thick and in this application a 4 x 50mm screw seems about right but that is just a guess.

After posting I was thinking could a pair be used with one clamping and the other spreading in opposition to hold something aligned against a single anchor point?

Oh so these things can be used in spreader mode. I cannot imagine when that need would arise given my limited DIY plans post house build completion. I do intend to make many internal Victorian style window shutters after moving into the new build as these are hideously expensive when custom made.