All Activity

For anyone browsing this in the future these BG electric ones are fantastic. Really thick and nice, not many holes. Highly recommended. At £2 ish each also not much more over the plastic junk. I should have never really been put in this position let alone having to cut all these out, but at least these are a nice solution

Good first go. A few comments: 1/ Your cavity tray is only one course above finished ground. BC will and I will pull you up on that. 2/ The insulation shown as a triangle just below the cavity tray is unbuildable as detailed . You are concentrating on the technicalities rather than balancing this with what is buildable, the cost and how you are going to make sure that what you are paying for actually happens on site. Don't blame yourself.. as unless you do this as a day job and have a feeling of build cost there is no way of you knowing this. 3/ You have a wide cavity. Why not thicken the perimeter insulation up to 100 or more thickness. Have a look at how MBC do an insulated raft slab and pinch their ideas. Then you can omit the Marmox block unless you want to spend money. You could be pragmatic and use the same money in a better way and in the round still achieve what you are looking to do.

Watch this like a hawk. You TA is probably in a loss position. Double check if you have any fire protection and if any changes alter the design intent. Check if you are changing the exposure rating and make sure this is ok in terms of your detailng and wind driven rain. Go back and just have a look at what you have done so far. You have learnt a lot. Don't bury you head in the sand and hope it will be ok. If it turns out you have dropped a bollock then now is the time to address.

Could someone tell me: I have the HW temp set to 46*C. Does this temperature have any bearing on the temperature the rads emit? Thx Zoot

I'm very impressed from what I could see. It took you two hours!.. well you are sharp as a tack. No way could I have churned that out in two hours.. even the small bit I can see. You're probably a bit like me.. as an SE / desinger I spend most of my time thinking and how I'm going to communicate the information so everyone can understand it, lots of folk are reluctant to pay for that. I know I have to produce structural calculations.. which after a while are not that envigorating when doing day to day stuff. I like maths but up to a point and get excited when I have to design whacky stuff. You are more adapt and nimble at high level maths than I. Far all. The idea is that you do the thinking, plan out how you are going to set up the calculation pack do the supporting drawings, bite the bullet and just get on with it. Then you have to check your sums and design philosophy is still valid. Is there any way you can make it idiot proof at my end so I can open it in excel? The reason for me pressing is this. When I joined BH it was as a result of a prompt. At the time Jeremy Harris (JH) was someone that floated my boat, he popped up again a while back but then went back into retirement. His thermal loss spreadsheet must have been used by many thousands of folk. Life has moved on but your spreadsheet has, from what I can see has potential. It's something that I would want to interrogate, see where the limits are, the best way to use it. I design insulated raft slabs for example, done it for years. But I can see there is potential for tweaking the perimeter insulation to extend down towards the foundation. This can make a big difference if the site conditions are ameniable. The actual type of soil under an insulated slab and around the underbuilding can have a huge impact as does the mobility of any ground water. @saveasteading is probably the best exponent of this practical art on BH as he has actually built hundreds if not more. At the end of the day the key to designing for self builders is to keep it as simple as possible, even if everything is not prefect. This allows for example a local builder with limited knwoledge, who does not have access to specialist trades to compete for and have a chance of delivering what you are paying for. @SteamyTeaYour absolutely right to highlight the form factor for example.. that is one bit I could see. I tried to track you formulae but the references are not familiar to me. But in the round my feeling is that you are introducing the next generation spreadsheet. call it Jeremy mark two?

I'm never going to understand the basics of the difference between this ON setting that I thought was being suggested, & this timer setting that I thought wasn't being suggested. I've tried today to read BB's link he sent me, but it's for the black controller vrc720, furthermore I'm lost immediately on the most seemingly simple stuff. Basic settings. I think the only way forward, is saying maybe what I don't want. And seeing if something fits around this. So what I don't want, is the heating on overnight. I don't want the heat, the wasted cost, nor any mechanical noise (absolutely fumdamental is no machinery "wakes up" kicking into gear at 3am, no murmerings/ nothing/ not even outside cos some noise transmits via pipes, into bedrooms, the very rooms you least want mechanical noise entering at 3am). Thanks, Zoot

A ground bearing slab means the inner leaf is built directly off the foundations.

It's fine. I've got back to the TA regarding the blocks and he is liaising with the company who did the SAP calcs to find out whether a medium density block will result in the target 0.18 value.

Hi BB, no the VRC700 is not in a hot tiny enclosure with the cylinder.. I don't think any installer would be -that- inept. It's where it was, in the small bedroom on a wall outside the cylinder enclosure (this thin wall is never ever, even barely warm). This bedroom is gonna be the warmest, cos it's the smallest, cos it's got the cylinder in the corner enclosure... but it's still a feckin freezing cold room compared to yours! It's got cold loft air behind the plasterboard walls, no insulation bar loft fluff above, & a cold sittingroom below it. Only way I can move the thermostat is buying 30m of cable & running it thru an attic, drill hole in ceiling, run cable down to kitchen/ thermostat there. But this room is SOO damn cold, 2nd coldest (one reason is bc there's no convenient wall to put anything but a single small double rad on: a mini fan heater is FAR better at heating this mostly ininsulated room, than this small rad ever does, or could ever do I reckon). I don't think this is a sensible place to put it myself, as surely just --too-- cold?? Anyway point is I can't afford to buy new wireless thermostat/ transmitter- receivers. Nor can I afford a plumber to reposition this vrc700. Nor will V likely send me a vrc720. So it's me do the job, if a freezing cold room is a sensible place for it.. rather than merely a cold room. Thanks, Zoot

It looks like from my end you have done your very best but are in a bit of a bind. The key thing here is not to blame yourself. Many find themselves in your position where you come to discover that the design packages you have don't cover all of the design and the interfaces don't fit up. Your strategic risk is that you make changes from what has been approved "in outline".. the BC inspector turns up later and says "you have changed stuff" and there is going to be no completion certificate until you justify the changes. Your design team to date are likely to wash their hands and set you adrift. At that point you may not be even able to sell the house. Have you considered trying to find a supportive designer that will take say a half day talking to you on the phone, then another two / three days reviewing your design, doing some fag packet calcs.. trying to to get their head round what you have done and the way forward, then at least another day talking to you on the phone, thrashing out you options. Call that 6 days work @ £400.0 a day = £2.4k You'll need a very experienced designer, one that undestands structures , maybe with a building background and with a bit of Architectural flair. Now that may seem a lot but even if they save you a weeks work and a day or so for a good trades person and a labourer then they have washed their face.

I like the idea of a shadow gap, but getting the detailing right looks tricky!

It reduces thermal bridging at the wall/floor junction, so helps with SAP calculation. I'm sure I remember reading an old thread on here that discussed relative performance of a row of marmox blocks versus lightweight, if you can find it

I have just installed our Mira stone resin tray (900 x 1700) installation methods vary manufacturer to manufacturer. Mira recommends bed on a weak sand and cement mix or use a suitable construction adhesive. Their tech help confirmed CT1 would be suitable. I tried the sand/cement mix but wasn’t happy so cleaned it up and redone using a few tubes of clear CT1. Took a leap of faith with the level because once laid in position I could not prize it up off the adhesive. I had lowered with banding straps which snapped when I tried the lift. Left 24hrs and all solid and level. Check out what Rodger says on the skill builder YouTube channel. I preferred the clear CT1 for this task. Thought process being that it’s a bit thicker in consistency than the white and the bed needed to make up a 3mm gap. our previous tray which I installed approx 10 years ago was bedded on the sand and cement mix which was good for years but then developed creaking noises but no obvious movement? On removal,the bedding mix was all cracked and turning to dust. I read everything the Welsh Wizard posts, he is amazing but do check out skill builder. Mira also told me not to use tile adhesive. You don’t want to bond the tray in position. Even flexi tile adhesive won’t allow for the different expansion movements. The indecision is a painful. You already have a suitable adhesive if that helps. How much of a bed do you need to make up under the tray?

I use Rye Oils, cedar oil, one single coat lasts a couple of years, now done two coats and 5 years in and is due a coat before summer.

It was, on this very boiler, but in another Site/Thread, "Bypass Valve" in DIYnot.com, the pump speed fell to 30% which by my calcs meant a flowrate of 6.3LPM at a head of only 0.35M, shared through 11 Type22 & 4 Triple rads. This was before the boiler HEX was changed, so yes, would be interesting to see a full set of data if tried again.

But of practical food for thought and info. 32 inches is about 800 mm. The ceiling ties you have are "economic and serving to hold the head of the wall against moving sideways. It's a basic garage after all. Next is if you have an attic say in a house what loads do the design codes prescribe? Well there are 3 types of load: 1 / The dead (permanent load) which is the self weight of the timber joists and the flooring. 2/ Where the space is habitable the load from people is 1.5 kN/m^2 (~150 kg/ sq metre) in domestic stuff = about 150 kg. This is an onerous load and not really applicable in your case. 3/ Attic storage is 25kg / sq metre.. but that includes the weight of the flooring.. so it works out at about 10 - 11 kg per square metre that you can use to store your xmas trees and empty suitceses etc. If it was a domestic floor (150 kg / m sq) then I would start using an old rule of thumb. It's ok to do this as your garage is probably built in feet / inches so why not use this as a basis. 3.3m ~ 129 inches which is about 11 feet. Divide 11 feet by 2 = 5.5 then add 2 = 7.5 inches depth based on a 2 foot spacing. 7.5" = 7.5 x 25.4 = 190mm! But at 400 mm centres that will drop below 170mm depth. Or lets say we can live with a bit more delfection and a reduced load. The rule of thumb is just to add 1 instead of 2 to the calculation above. This now gives.. divide 11 feet by 2 = 5.5 the add 1 = 6.5 inches depth based on a 2 foot spacing. = 6.5 x 25.4 = 165mm. In summary what I have done above just confirms your first thoughts are in line with normal expectation.. 145 - 170 deep timbers if you put them in at say 400 mm centres look at the moment adequate. I suspect that if you spent more time refining the loads then a 145 mm deep timber in C24 would be ok. After all there is only so much load you can get in there (unless you do something daft) due to the diminishing height as you appraoch the eaves. The main thing here is that the difference in cost between 170 and 145 deep joists is not a lot.. it's the head room and making sure you can open the doors that is key. Can you just essentially leave the roof as it is and introduce an independent floor? This might be possible if you have a timber wall plate on top of the wall. On the inside of the wall you fix a ledger piece, then use wrap over joist hangers with the wrp onto the existing wall plate. The beauty of this is that it's nearly all demountable so you get to recover the joists, flooring if you screw it down and not glue it, live with any squeeks! One last thing though.. you need to have a look at the walls and what they are sitting on, do you have any door openings below the new joists.. think lintel strength. If you add load you have to be sure the walls and founds are not going to misbehave.

even in my case where from the back of the window frame, its cavity wall pir insulation then the internal block? if that makes sense.

I shouldn't think so, but I don't really know, because I didn't learn about ground bearing slabs before I designed my house. I should think with a ground bearing slab, you'd have a continuous platform of insulation to separate the top part of slab (including the bit the walls are built off) from the bit that's in contact with the ground. In my case, I have concrete foundations with trench blocks, & the trench blocks support a beam & block structure, so my inner masonry leaf would have a direct connection to the ground, through low R-value materials, were it not for the Marmox blocks. Perhaps I should have left this question for somebody more knowledgeable than me to answer, but it seemed to be directed at me.

Was about 2 hours, over a coffee, but 45 years of studying.

From what I could see it look like a very useful tool. You are being bashfull! It's not something you knock up and check in an hour or so!

Essential, not just good!

Yeah, that's what I did with the plywood sheets I used for the stringers for my construction stairs. They have a delightful bounce to them but have been plenty strong enough 😁

Ah yes, indeed. I just reread the technical document I had and realised that what I read - Differential Pressure Delta P - was just constant pressure not proportional, which is why I was confused by the chart showing constant pressure. I must read these things a bit more carefully next time! I think it's worth testing pump setting 0 to see what happens. Who knows, it may not work at all but if it were me, I'd like to see variation in flow rate proportional to burner and DT and then see what happens through the system. I wonder what happens when these things are installed with weather compensation, or maybe nobody ever does and they build these things for relay controls only for the UK market, just like other manufacturers like to reduce specs for us?

Use an adhesive. You could do a couple of tests and see how it 'feels'.

Good question. I hadn't really thought about it this way but may not be practical given the span is 3.3m so I'd have to sister the plywood sheets too.