How to ensure walls all level for intermediate floor?

[ruggers]

Looking to start a self build brick construction. How do I ensure that all of my internal load bearing walls match up in height with my inner leaf cavity walls so that the posi joists are supported correctly without bows/dips. A couple of my Posi joists also span the full width of the build and rest on a couple of internal room dividing walls. Not all builders work to the same standard, some might use lasers for this, what should i be looking for to ensure the best results possible?

 

The ends of the joists will be supported by internal masonry hangers, joist depth is 253mm which isn't ideal to tie in with brick/block course very well.

[twice round the block]

I think I have read your question correctly  so here goes.

I just bed timber wall plates on top 0f the walls into a mortar mix and tap level. When I come to do the joists, find the highest one and put packers in the joist hangers in  all the others so they all end up level. 

Take time at getting this spot on as there is nothing worse than a slopping floor in a room or section of the house and it's a sod to sort out at a later date.

[ruggers]

I'm aware of bedding a timber wall plate onto cement at the top of the build to sit the roof trusses onto. But wasn't aware its done at intermediate floor level.

 

So some of my joists ends will be supported by sitting into a masonry joist hanger which will bed down between the courses of the inner block work with the opposite end of the joists resting on on my load bearing internal partition walls also constructed from blocks. I'm not sure if they sit direct onto these inner walls or there also needs to be a 100 x 50mm wall plate too? I wouldn't of thought there would be, and so the internal walls and the cavity wall inner skin wall courses need to match up in courses.

 

I will also have some joists 11.45m long that will span the full house width and each end will be secured into a masonry joist hanger, but mid way along this span will be two internal walls and if the top of these walls were, lets say 10mm higher or lower than the masonry hangers, then the long joists would be bowed.

[Iceverge]

A better detail would be a ledger board bolted to the wall external walls and the hangers hung on this. Parge the wall behind it and then and then set a line with a laser. Use chemical anchors to secure threaded bars and bolt it home. 

 Much easier to get airtight and level than hangers built in by the masons. 

 

The inner wall plate can be done last. Just get it close enough with the blocks and leave enough space for a wall plate + a morter bed. By varying the thickness of timber and mortar you'll be able to make up any height from about 40mm to 100mm. 

[Canski]

We use a laser and put datum marks usually 1m above finished floor level around the buildings corners. . We then build the corners up to the desired height then run the walls in. You can get a bit of line sag on a long run so we usually tingle the line to a datum in the middle of a long run. 

[ruggers]

On 04/08/2022 at 19:03, Iceverge said:

A better detail would be a ledger board bolted to the wall external walls and the hangers hung on this. Parge the wall behind it and then and then set a line with a laser. Use chemical anchors to secure threaded bars and bolt it home. 

 Much easier to get airtight and level than hangers built in by the masons. 

 

The inner wall plate can be done last. Just get it close enough with the blocks and leave enough space for a wall plate + a morter bed. By varying the thickness of timber and mortar you'll be able to make up any height from about 40mm to 100mm. 

I agree with you that for ease of installation and air tightness this is the winner, i had a post about these options a few months ago, ledger board vs masonry hangers vs tony tray vs just built in as standard. Because the ledger board sitting tight to the inner face of the wall prevented all of my services reaching the consumer, it meant that the ledger would need packed off the wall by 25mm or so which I don't see as an issue. But I struggled to get certain people to agree because it wasn't something they've experienced before, my plans were 'well' over due completion and I just needed them complete to get on with it. They are passed now but it might be worth me checking with a structural engineer to ask if we can change it. It doesn't affect the plans.

Trying to hope the mid span walls tally up in height with the underside of the masonry hangers won't be easy at all.

On 04/08/2022 at 19:47, Canski said:

We use a laser and put datum marks usually 1m above finished floor level around the buildings corners. . We then build the corners up to the desired height then run the walls in. You can get a bit of line sag on a long run so we usually tingle the line to a datum in the middle of a long run. 

Thanks Canski, I will meet up with the builder and ask what they do and suggest this option. What is classed as a long line, my largest span will be 12m. When posi joists are supported at each end via masonry hangers, any mid span load bearing walls they cross over and rest on, do the joists rest directly onto the block work, or would a timber wall plate be bedded on, the same as you do at the top wall plate for the trusses?

[Canski]

On 12 m I would use a tingle in the middle measured up from a datum. Joists would usually just rest on the masonry on the intermediate walls and be infilled with block or brickwork. 
 

best get your gold Amex card out 😀

 

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjBjK3nprL5AhWgS0EAHWUuCKAQwqsBegQIBRAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DDjEh1tMC62U&usg=AOvVaw3czXIdAO9jD_VaKaQ73cZs

[ruggers]

Handy little trick. If the joists are blocked up in between them over internal walls, there won't be any space for running the services in the floor void between rooms? Cables, pipes, MVHR ducting.

[Canski]

Ruggers you are correct. the other trades just smash them out with a JCB or similar. Some remain some don’t make it. 

[ruggers]

So i sense a level or sarcasm but are you suggesting posi joist do or don't get blocked up between. Bricking between will help prevent cross travel of sound but services don't just run in one place so there would be a good few missing. I worked out then the 253mm joists if they on hangers would sit well mid span on a 100x47mm timber underneath to tie in with the brick courses but this means you definitely cant brick between.

[Canski]

Sorry I didn't mean to sound sarcastic. I was referring to the following trades who are not used to having blockwork in their service runs and get a bit hammer happy.  It depends who we are building for. All of my clients use posi joists and some ask for the gaps to be blocked up and some don't. The ones that do insist that the pipe and cable runs are drilled through the blockwork avoiding damage. As property developers None of them use MVHR and none of them have ever used a wall plate beneath the joists on intermediate walls . I'm not saying it can't be done only that we have never done it. It is just as easy and with the state of timber these days it's more accurate to build them in blockwork.

[ruggers]

@Canski Thanks for the advice. If the intermediate walls were laser marked like previously described 1m below, it could work out better, but due to the posi joists being 253mm not 225 or 300, I'm thinking it's a bummer for someone to cut 28mm off each block and wouldn't end up very tidy.

 

2 bricks and a 47mm could make it a lot easier to tie back in with the cavity courses. It's all mathematical and the real world doesn't work this way especially if blocks are cut with bolsters rather than saw cut.