epsilonGreedy

Possibly because your stove is a smallish model with (guess) a 5Kw output? We initially settled on a 12kw stove for its looks until advised that would be bonkers in a new build. I also theorise that your trad wet plaster walls can soak up excess heat more quickly than dry lined dot & dab. You seem to have got so much right in your project, was it your first self build? We have sized the fireplace for an 8kw model with external air supply, the open plan sitting room with stairs to the landing should help distribute excess heat in our case.

To kick start a wood burner into a good clean hot burn the stove will initially output near the top end of its quoted range. It will then be difficult to maintain a consistent burn at the low end range before you resort to opening windows to shed excess kW. Clearview have a strong opinion on this to the point of losing sales of larger models.

In the end we treated ourselves to a short break in Ludlow and spent a few hours looking around the Clearview stoves showroom. The showroom is based in a Georgian era house which provided inspiration for the style of our newbuild, the staff there are very knowledgeable. If depth constrained we noted that a stove can project 50mm forward of the face of the chimney breast. The staff at clearview talked us down from a large stove and said anything over 8kw is nuts in a new build. Treat the low end of kW output ranges with a pinch of salt. We demolished our first chimney breast and rebuilt after our showroom visit. Have you sorted out the technicalities of the air feed?

I ordered 47kg bottles today, delivery promised tomorrow or Wednesday. The price per bottle has gone up 8% since the summer.

Most of my main hipped roof trusses are up and this morning I was going to trim the hip rafter ends so that the top of the hip rafters seated flat against the ridge end truss. My roof pitch is 30 degrees and I assumed the settings for my compound mitre saw would be a 45 degree bevel because the hip rafters bisect 90 degrees and the other setting would be 30 degrees matching the pitch. The hip rafters were supplied with angled cut off ends which I assumed were 30 degrees. My expectation was that with the mitre saw configured for a 30+45 compound cut I would slide the hip rafter end along to the cutting point and just slice off the 45 degree bevel. It turns out the hip after ends are cut to 24 degrees and not 30. I decided to double check and offered up the hip rafter to the roof trusses already erected and it turns out 24 degrees is correct. Before trimming my hip rafters I thought it best to check here that I am not seeing things. I have tried to visualize the trigonometry by imagining sweeping a rafter through 90 degrees at the hip end. The angle of intersection must start and end at 30 degrees but half way through the sweep the pitch angle is 24 degrees. Part way through this visualization my head explodes.

Is LPG a by-product of general oil extraction and refining? If so then with travel mileage (road & air) way down in the West this could be the explanation .

@Gus Potterthank you for your extensive reply. Distilling your post down to the essentials my takeaway is that local vortices above parts of a roof are the most likely source of roof wind damage and in this case the damage will be to the cover. Looking more broadly at wind stresses on the whole roof structure, a large proportion of the roof should not be subject to simultaneous uplift strong enough to cause trusses to tear off their wall plate clips. True in part, however a correctly trimmed sail should have a laminar airflow like an aircraft wing. The winning edge on a racing yacht is obtained through encouraging just a hint of a vortex along the leading vertical edge of a sail but not enough to develop a large volume of turbulence behind the sail. I can see some similarity between the cross section of a low pitch roof, yacht sail and aircraft wing. Unfortunately my house will not come equipped with a mainsheet that can be released during a storm force gust to spill the wind hence my interest. The power in a sail is ultimately derived from slowing down the airflow and extracting kinetic energy from the moving airflow. Going back to O level physics and E = Mass * Velocity squared * 0.5 then at 80 mph the forces get disconcerting i.e. a routine 40 mph gale force gust has 4 times less energy than a winter storm 80mph gust. In 80 mph a yacht will be running under a bear mast at a surprising speed whereas 40 mph is just a nasty gale where some sail is left up for control. Getting back to my 30 degree roof after some further reading I understand that 10 to 15 degrees is the pitch most likely to start behaving like an aircraft wing with associated lift. 30 degrees is still a concern.

I should do that but rarely do. Three years is useful.

Ok I am an idiot. It turns out the calibrated and curved depth locking is marked in big centimeters that look like inches. The reason for this is that scale on the lock is twice the distance of the blade from the depth adjustment pivot, so 1 big cm on the scale = 1 normal cm of blade below the base plate. Over the years I have become alert to mail order outfits substituting non UK stock, I once bought a Sebo vacuUm from Amazon that arrived with a euro to UK plug adaptor and for the next 10 years the adaptor used to get wedged in the flex recoil mechanism. Then last year a dodgy Welsh power tool retailer sold me a few Makita items in a plain cardboard box with no Makita paperwork.

Makita DHS680Z Brushless 18 V Li-ion Circular. https://www.amazon.co.uk/gp/product/B00WW83F4Q/

It was a brushless 18v model sold and dispatched by Amazon. The point of contention is that the blade depth gauge is marked in inches but I think in mm below a foot. Should a proper UK model's cut depth gauge be marked in mm's?

I decided to calculate the weight of my main roof which is 105 m2 including the eave overhang. The trusses are about 1.2 tons and the slate is 4.4 tons, so call it 6 tons including the battens. There are 58 truss and jack rafter seating points on the wall plate = 103 kg per seat. I expect the central trusses will place a larger load and the minor corner hip end jacks much less than 103kg. Pleased now that I fitted heavy window lintels. I am unable to calculate the lift force on the on the lee side of a 30 degree hipped roof but I know that a 40 mph wind striking 60m2 of sail will pin a 6 ton yacht on its side

Hmm yes. I suppose my thinking has been driven by a concern over cyclical loading and the thought of the metal nail opening up a wobbly hole in the block over the years. Given the strong trade preference for nailing in straps I wonder why NHBC and the likes of Simson even bother to specify rawplugs and wood screws as a solution. Ok so now my option is 70mm long regular masonry nails as specified in the NHBC extract above or the Hilti nails with a washer as mentioned by @Declan52

From your previous posts I get the impression that in Northern Ireland medium and heavy blocks are used. Do you think masonry nails into light blocks works just a well for a wallplate strap?

I have an irrational mental block about nailing metal into masonry, I just feel it is better to torque up a fixing with an intermediate material (rawplug) progressively taking up the strain. If I nailed in these wallplate straps then during every winter gale I would imagine the masonry nails gradually opening up their holes in each storm force gust and then working loose.

Just need to clarify. If say the recommended wall plug hole diameter is 7mm you would drill using a 6.5mm bit?

I have a boring question about selection of wall plugs for fixing roof wallplate straps into the wall. The NHBC advise: HOLDING DOWN STRAPS If the design specifies holding down straps to prevent the roof being lifted off the supporting structure, they should be at 2.0m centres (maximum). Where straps are fixed to masonry, hardened nails 4mm in diameter x 75mm long or No 12 wood screws x 50mm long into plugs should be used. The number of fixings should be in accordance with design requirements and the lowest fixing should be within 150mm of the bottom of the vertical strap The NHBC diagram also states at least 4 fixings per strap. http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part7/section2/sitework.htm If I take the No 12 x 50mm long wood screw option what rawplug should I buy? Given that these screws effectively prevent the roof lifting off in a storm I am thinking hole size and rawplug type is more critical than fixing a curtain pole. I am fixing to Plasmore fibolites which are classed a lightweight block but at 8kg a block they have a bit more meat than the lighter aerated blocks. This following page is useful. A No12 wood screw is 5.5mm metric and the reference table suggest a 7mm hole with a brown wall plug. https://handycrowd.com/screws-explained-gauge-size-pilot-holes-and-wall-plugs/ If this info is correct I reckon my only remaining question is, do I need some special high load rawplug? Actually one more question. Should the raw plug be longer or shorter than the screw length?

No, you are correct. The imprinted spec on the hanger says: So 12 square nails and 6 round wire nails per hanger. There is no such spec on the clips used where the trusses seat on the wallplate. As I consider wind stresses on the finished roof I realise the fixing of these clips is vital as well i.e. no point in study straps holding down the wall plate if the trusses tear out their seating clips. I recall your roof had direct truss to wall twisted straps?

I take your point. Speed is way down the priority list of this bumbling self builder. I think internet research is taking much longer than the hammering part of this roofing job ?

The nail spec imprinted on the joist hangers specifies "round wire nails" 3.75 x 75. Are ring shank nails a good substitute for round wire nails on a roofing job where a manual hammer is the chosen weapon?

I blame YouTube for this idea. I was researching how to approach fixing a fascia and soffit and found a British guy describing the same job on his renovation, he has painted his wooden eaves with linseed paint. It is claimed the paint will protect the wood for longer in this awkward to maintain area. Reading some more I understand a linseed based paint will penetrate the wood better. Given that water entrapment behind a flaking modern "plastic" paint is the likely mechanism of rotting eaves, I quite like the idea of using this stuff on my eaves. Conversely I am not sure why an oil paint will penetrate wood better than water based paint, thinking back to O level chemistry oil molecules are long and stringy but a water molecule is small. Linseed paints take longer to dry apparently which could be an issue at this time of year. https://www.linseedpaint.com/

Ah, shear force. Not considered that, makes sense. Previously I considered wood jointing to be mainly a bonding challenge.

If I was self building on a desert island with no internet connection for reference I would connect all bits of wood with screws. A screw seems like an inherently superior method of pulling two bits of wood together compared to a nail. Is there any downside putting up trusses with screws instead of nails?

I should also buy myself one of those lipped set squares that Robin Clevit uses on SkillBuilder. My set square is a simpler model, the same I used during carpentry lessons at school aged 14.

I will start with a small single storey section of roof which is 8' x 12'. The trusses are tiny and can be lifted in one hand. My compound mitre saw should be good for the two hip rafters plus jacks and there is a good SkillBuilder episode on the finer points of cutting hips.