MortarThePoint

Looks very smart, good job!

You're right, it was just a new thing to think about but as you say you won't notice it as it's in shade anyway.

That's a good option. I wondered if anyone does a sort of sleeve that can tuck over the lintel, it could even have the cavity tray built in

This may be daft question, but how do you conceal the outer part of a window or door lintel in brickwork. The brickwork above the lintel is sat on top of the lintel and I don't want to be able to see the metal underside of the lintel when finished. What are my options? I know you can get special soldier course lintels but we don't want a soldier course. Feels easier to hide it in walls that are rendered, but bare brickwork walls feel harder to hide the lintels in. Do people just paint the lintel? More RAL charts with the wife if so which isn't my favourite activity.

I'm confused now. Is that 250 bricks a day then when the going is hard and then 650 bricks a day when running in?

I'm clearly in the wrong line of work ? 250 a day and 650 per thousand bricks equates to 380 bricks a day which feels a bit pedestrian.

So did the 5 months dry out the block throughout and then it was important to make the surface wet to help the plaster?

Is that £650 labour cost per thousand bricks laid? That's £39/m2.

Out of interest, do you know if the Naylor P215 is a composite lintel or not?

Yes it is only 65 deep. Thank you for the insight.

I just looked and a P215 appears to have an unfactored UDL of 27kN/m, but would that be in the A frame scenario?

Thanks @Gus Potter, very informative. There is a door immediately above the floor slab that bears on the lintel. The load from that is 17kN/m but there's no scope for composite action. They did swap it to a P215 lintel. There is a helper pillar breaking the span into 2 spans, a 650mm span and a 300mm span. There's concrete packing underneath the lintel but of unknown quality and therefore unknown strength.

Thanks nod. That amounts to a higher cost per m2. Bear in mind a m2 price would often be quoted already having factored in time spent doing openings etc. 600 bricks a day doesn't feel a stretch if not doing openings etc, but I speak without much experience other than watching videos and laying bricks myself as if I have two left arms and someone turned out the lights.

I like playing with Excel to understand things and have knocked up a cost estimator for brickwork and blockwork labour. I hope that the figures in it are relatively conservative. A lot of the figures are finger to the wind, so let me know what you think. Ideally, it could prove a handy tool for others to get a feel for what the rough cost should be. Some of the main assumptions are highlighted and are: Day rates - I've used £200 for a brickie and £100 for a labourer. I chose round numbers as everyone's local rate will be different. Bricks per day - I've assumed 600 stretcher bond bricks/brickie/day which should be on the low side, so consistent with the quality level us lot typically want. Blocks per day - I've assumed just over 2 minutes per 100mm medium density block lay which gives 20m2/brickie/day. There are then speed factors for heavier or lighter blocks. That handles the area based work. There is a section for things that are on an item basis like windows, steels and chimney tops and costed on the basis of quantity and serviced brickie hours each. As examples, I have assumed that it takes: a brickie 2 hours to install all the extras needed for a window opening (i.e. cavity closers, lintel, cavity tray and weep holes) 2 brickies and a labourer half a day to install a moderately large steel beam a brickie 3 hours to install a wind post on the basis of them being uncommon on the job. As I said, the numbers are a starting point. It would be interesting to see if we could get some more realistic numbers in there though. ? Brickie_Labour_Cost_Estimator_BUILDHUBv0.xlsx

I'm learning on this, but there is also a lot of marketing at play around blocks. I feel there is a clear distinction to be drawn between aerated blocks (AAC) and aggregate blocks. AAC blocks "Unlike most other concrete applications, AAC is produced using no aggregate larger than sand. Quartz sand, calcined gypsum, lime (mineral) and/or cement and water are used as a binding agent. Aluminum powder is used at a rate of 0.05%–0.08% by volume (depending on the pre-specified density). In some countries, like India and China, fly ash generated from coal fire power plants and having 50-65% silica content is used as an aggregate. When AAC is mixed and cast in forms, several chemical reactions take place that gives AAC its light weight (20% of the weight of concrete) and thermal properties. Aluminum powder reacts with calcium hydroxide and water to form hydrogen. The hydrogen gas foams and doubles the volume of the raw mix creating gas bubbles up to 3mm (⅛ inch) in diameter. At the end of the foaming process, the hydrogen escapes into the atmosphere and is replaced by air." Wikipedia Thermalite and Celcon etc are AAC blocks that have a density in the region of 450 - 800kg/m3 and lambda of around 0.11 - 0.20 W/mK. Whilst easy to handle and thermally performant, these are the blocks that people typically worry about cracking. The article linked above notes as a disadvantage: "Installation during rainy weather: AAC is known to crack after installation, which can be avoided by reducing the strength of the mortar and ensuring the blocks are dry during and after installation." Aggregate blocks It's a bit more obvious how these are made, consisting of cement and aggregate. Typically available as Dense (~1900kg/m3) , Medium, Lightweight (~1400kg/m3) and Ultra Lightweight (~1000kg/m3) this refers to the aggregate type used in their manufacture. The marketing department has done well to describe a 100mm block weighing over 10kg as Ultra Lightweight and this is twice the weight of the equivalent AAC block. Their reduced weight comes from the use of naturally occurring (e.g. pummice) or man made (expanded clay, blast-furnace slag) aerated aggregate. As well as reducing weight, this lowers the lambda values, with 0.28W/mK available in Ultra Lightweight aggregate blocks. Comparison Obviously both block types have their place, but personally I'm inclined to avoid AAC. They have exceptional lambda values and can be half the weight of even the lightest aggregate blocks, but they can be unforgiving and present future problems. Not as good thermally, Ultra Lightweight aggregate blocks do provide a useful improvement in wall U-values over using denser blocks. The aggregate itself in Ultra Lightweight aggregate blocks won't be as strong as in Dense aggregate blocks, but the mechanical properties of an aggregate block will be a function of the aggregate and how well the aggregate is held together. Aggregate blocks aren't immune to cracking. It may be obvious, but cracking happens due to movement so eliminating the sources of that movement is a key part of avoiding them. Shrinkage is one of the key reasons cracking could occur and avoiding the blocks becoming excessively wet can reduce this risk. There are some scary picture here. Another reference: Forterra Pocket guide to Aggregate Blocks

Fibolites seem to have 3dB less attenuation than Stranlites. I think that means the transmitted sound energy is double in the case of Fibolite. I don't know what a stud wall looks like in terms of sound attenuation though for comparison. Fibolite 100mm (850 kg/m3) : https://www.plasmor.co.uk/uploads/files/Technical_Library/Technical_Data_&_Reports/Acoustic Test Certificates/100mm_Fibolite_-_Plastered.pdf Stranlite 100mm (1400 kg/m3) : https://www.plasmor.co.uk/uploads/files/Technical_Library/Technical_Data_&_Reports/Acoustic Test Certificates/100mm_Stranlite_-_Plastered.pdf

I'm ordering the blocks (ouch) and made a decision I thought I'd gauge people's thoughts on [over-analysing hat on again]. I decided to stick with a single 7.3N block type, rather than using 7.3N Fibolite for the inner leaf of exterior walls and 7.3N Stranlite for the load bearing partitions. So Fibolites for both wall types. I saw the pros and cons as: Pro's to using Fibolite internally: single block type for brickies order simplicity Con's cost (51.4m2 @ £1.52/m2 difference --> £78.18) acoustics? lower thermal mass (950 vs 1350) Bit worried about the acoustic side of it. Does anyone have any experience of how well Fibolite blocks damp sound?

Good thought, I've just emailed them so fingers crossed. They haven't been hugely forthcoming we details so far though.

Below is what I now understand would be the normal situation for a beam & block floor with insulation and screed carrying on across the cavity. If I carried on the screed across the cavity: With EPS sheet insulation added in to void below:

The EPS or PIR would be a vertical sheet in the cavity. Remember that the EPS of the floor is prefab into the floor so ends at the edge of the cavity. I guess the EPS or PIR could be cut to the height of the cavity at that point so it is bearing on the cavity fill concrete at the base of the cavity, but I wouldn't have thought that is very strong. EPS squishes pretty easily. That leaves the screed as the only truly structural part doesn't it?

@PeterW and @Mr Punter , I think you're both suggesting I put EPS in the cavity below the membrane and then screed over the top of that. That makes the screed the only structural part of that and it's only 35mm thick cantilevering over a 100mm cavity. That makes me a bit nervous it could crack under load.

I should have explained, the shaded grey part is the concrete element of the Thermabeam floor and the EPS is prebonded to that. You can see the EPS in the photo of the end of a Thermabeam slab below which is a darker grey than the concrete. The EPS extends all the way to the edge of the cavity and some concrete pillars cut through it to support the slab and the wall above it.

Thanks no, looks good. If I understand correctly, that is some membrane taped (on both sides) to the membrane that is coming up from under the beam&block? That membrane is then passed over the PIR insulation.

Does anyone have a door sill threshold detail I can have a look at? It's not for a level threshold, but I am finding it difficult to find a drawing. I am unclear what goes under the door sill (see red arrow). Should there be an insulated cavity closer there underneath the door sill? I am using blown bead insulation, so more broadly need to understand if insulated cavity closers are needed elsewhere anyway or if I can just use uninsulated cavity closers. I've used a sill height of 25mm. I am not sure if that is standard, but I saw one that was. It will be a timber sill. I have up to 50mm for screed and floor finish. I have probably put the door in the wrong place relative to the wall face, as I just popped it in roughly. The structural floor element is a precast concrete floor slab (Thermabeam) with insulation prebonded on its underside.

That does seem very high. I take it that price doesn't include the warranty. I don't know, but I guess it could be that conversions are more expensive than new builds as the underlying asset of the existing house is at risk. Do shop around as prices vary hugely. SelfBuildZone are another provider to try if you haven't already.