Subfloor and bricklaying in wet and freezing temps

[Sunil237]

Hi folks,

 

Current situation: My builder has excavated the trench and floor, laid the foundation and blocks/blue bricks to DPC. it has been raining so the ground is soft and has pools of water.

Next on the list: laying Type 1 and brick laying.

Weather problems: It is heavily raining tonight so the ground is going to be very saturated, and the weather for the rest of the week is a max of 2C for a few hours a day and freezing all evening/night with a max low of -6C.

 

My questions;

1) Can the ground be levelled and laid with type 1 whilst it's wet? They have said they will bail out any standing water, but they obviously can't do anything about the mushy soil/clay - ideally this is done tomorrow as they have the digger and dumper hired for the last day.

2) is brick laying compromised in these temps? from what I've read they shouldn't be laying below 2C but in practice is it ok?

3) would it be wise to get my BCO involved about this? I don't want to create a bad relationship with the builder as there's obviously so much to do still

 

Appreciated!

[DannyT]

To answer your bricklaying question.

Im ment to be back at work today but wont be going in. I won’t be laying a brick at all this week. Temps are not getting high enough and don’t let anyone tell you otherwise.

mortar will freeze and blow. Blue bricks can take day to dry on a good day. Cold weather they won’t set. Seen it many times. The standard was 3c and rising but with the lows we be having there’s no chance.

If they think it’s acceptable to carry on, you need to have a chat with them.

[Canski]

Have you got your drainage in yet ? If you are putting MOT on top of sloppy mud you will just make more sloppy mud. Mothball the site. I know it’s a waste of hire charges but I expect you would be paying labour on top of the hire and it’s all money down the drain. 

[Sunil237]

Hi, thanks. They agreed to not start the bricks so I'm happy with that.

 

They chose to do the MOT but have taken out surface water. I'm confident they haven't ordered enough mot to get to level so I'll expect another load to top it up later, I figure this is the best I'll get now.

They could have easily piled up the MOT in the driest corner and moved it around later but too late now unfortunately.

 

Thanks

[Temp]

+1 to what @DannyT said about temperatures.

 

They can/should also use an additive in the mortar. Don't let them use washing up liquid. I forget what the correct stuff is called but it's not expensive. You could buy it for them if necessary.

 

They should also cover up new/green work overnight.

 

[saveasteading]

3 degrees and rising is the guide for concrete.

I've broken this guidance once and it became expensive hardcore....it barely hardened, and then crumbled. 

The same will happen with mortar.

 

As for the type 1.   That shouldn't go down thicker than 150mm per layer and be compacted by roller. 

I hope you have membrane under it.

Compaction over mud  would press the stone down into the mud and it would mix if there is no membrane or just rut if there is.

Spreading with a tracked machine does not compact it, but is your best compromise for now....and don't run wheeled vehicles over it.

 

An experienced builder should know the basics of all this, buy many don't. 

They should also expect to lose working days in winter. It's not your responsibility to keep them earning at your risk.

It is too important to turn a blind eye.

More detail of the hardcore construction?

[Sunil237]

They are using the mortar additive so I'm happy about this. they haven't covered up the works well so far but I'll make sure it's covered once they start again, we will have a few days of dry weather now so it will be best that they let it breath.

 

Luckily today all they did was move about 2ton of MOT to a single spot in the excavated area and empty some of the water out. @saveasteadingcould you link me to a suitable membrane so I can go get it and ask them to lay this before spreading the MOT?

 

Here's my floor build:

50mm Cemfloor screed, UFH, Slip layer/Polysheet, 250mm Celotex PIR, 1200g DPM, 25mm sand blinded, 100mm concrete slab, VCL, 150mm MOT Type 1. 25mm upstand insulation all around.

[saveasteading]

8 minutes ago, Sunil237 said:

@saveasteadingcould you link me to a suitable membrane

Ask your local builders' merchant for a non-woven geotextile membrane.

If there is a choice of qualities then tell them the purpose, but it is going to need only middling quality  unless you will be driving trucks or buses on it regularly.

Terram is the best known name (like Hoover) but there are plenty of other suppliers.

 

12 minutes ago, Sunil237 said:

They are using the mortar additive so I'm happy about this.

Do follow the instructions precisely.  The materials should not be too cold, and it is clever, not magic.

 

Whether you should remove the cover to let it breathe is doubtful.

Mortar does not get its strength by drying out, but curing into a new material,  and needs water for the chemistry. Cement  normally takes 30 days to complete its chemical reaction and get the mortar to full strength, and it needs warmth and moisture for those. The additive speeds this all up, but I know no more. Perhaps the instructions say more.

[torre]

You've a challenge ahead building in this weather.

 

As others have said make sure all fresh brickwork is well covered, you'll want to try and keep the cavity covered too so your insulation isn't drenched. We've used cheap tarpaulins for this and it's a battle keeping things in place with high winds.

 

Also, make sure your bricks are covered on site so they're dryer when laid or that water is eventually going to push a lot of salts out of the bricks.

 

I'm a bit sceptical of winter mix additive, be cautious of your builder pushing to work in too low temperatures. If local sites around you aren't laying, you probably shouldn't be either

 

[MikeGrahamT21]

If its real cold, get a good fire going near your pile/bags of sand to get a small amount of heat in it, should help no end in -6C, but ideally, wait til next week when its a bit milder, never ideal i know!