DBT85s Workshop - Moved in and now time to fit it out

[MikeG.]

That looks text book. Just checking that you have screwed in from the outside....ie screwed through the stakes into the formwork, rather than from the inside (through the formwork into the stakes). You won't get it apart otherwise. It can sometimes be easier to site the stakes remotely and cut in a timber in between. This can be particularly useful if you've used hardcore, or have flinty ground. In your case this would mean whacking stakes into the grass, then wedging in some timber to prop up the formwork. There is tremendous outward pressure on formwork when it's full of wet concrete, so better to err on the generous side when it comes to props.

Your diagonals are bang on.......but levels are more important. Triple check those, won't you.

edit.......I've just noticed that the top of your stakes are above the top of the forms. You'll find this a real nuisance when you are tamping, so go around with a handsaw when you've finished and hack the tops off.

2nd edit .......have you got room to fit a brick and a 50mm block between the inside edge of the formwork and the ducting? They look a tad close to the edge to me, and once concrete is poured they're stuck. Shove a plastic bag in the end of each before you start splashing the concrete about, won't you.

 

[DBT85]

Ta chaps.

Don't worry I did screw the stakes in from the outside :lol:

I could put the stakes in the grass no issue, but its then supporting the board properly as they only just clear the surface of the ground and in places don't yet do that. Obviously if the slab was starting at ground level that would be easier. The amount of time it would take me to make individually sized horizontal supports and maybe a diagonal part to also brace the bottom of each point would be huge. I can just rummage the hardcore a bit much easier.

I think I calculated for a stake every 500mm and I have enough to do one every 550mm so I imagine that will suffice. I can always make more if it doesn't feel right.

Levels were double checked and I shall do so again with the laser before it goes back. I also need to check in the middle of the lengths once I get some stakes in.

Some of the stakes are indeed above the forms, don't worry they'll be out the way before Wednesday morning! Some are thumped down far enough that I don't need to cut them. They were 500mm long each.

There will be room for the ducting. There isn't at the moment as its being held back with string to keep it in its rough position. Once the mesh is in I can secure it to that in its proper location 160mm from the edge. At worst I'd have to make a minor notch in my block. I could do that with a spoon I think!

Once all of this is ready for Wednesday I'll make my block chopping jig up and get them all done.


Just ordered the 2core SWA from superlec direct. a fair bit cheaper than TLC which I was surprised at. £20 saving alone in delivery! That's another £122 on the list.

 

[gregmcateer]

That's properly exciting!
You must be jumping up and down as it starts.

One small thought- when we built my single garage/ workshop, we beefed up the ceiling joists and added a trap door, so I've gained some handy storage space in the roof space.

Looking forward to watching yours progress

 

[DBT85]

It is Greg!

No need for a trap door, the roof has 13 rafters but only 7 ties/joists. So there is a section at each end where I'll be able to store things and a 3m section in the middle that will be open all the way upto the underside of the rafters.

You might be able to see it in one of the drawings a bit further up.

 

[Yojevol]

Taking an interest in your project, I'm reminded of a water/moisture ingress problem I had with my workshop. It is a log cabin style structure built up on a course of bricks on a concrete base, ie similar to yours. From your drawings I see that you are proposing to build your brickwork right on the edge of the concrete. If I had done that my problem would have been reduced but not eliminated so I'll tell the story:-
The brick course was built about 6" from the edge of the slab. The building timbers were laid directly on the bricks. After a year or so a few cracks developed in the brick mortar which allowed water ingress resulting in puddles on my workshop floor. This was a problem only on the SW facing wall subject to prevailing wind and rain. It was particularly alarming because I had put in a line of tool cupboards along that wall.
I tried various methods of sealing but to no avail. Eventually it was evident that the whole wall was suffering from the elements so drastic action was needed. This is the result:-

Firstly I sealed the bricks to the slab with flexible plastic flashing. This was followed by cladding the entire wall with fibre shingles making sure they overlapped the flashing by a good margin. This system has been installed for about 4 years now and I've had no further problem.
With your design water falling off the walls will drain down the edge of the slab, but if cracks develop there may be a problem, although your 3 courses of bricks should be more stable than my single layer. It might be an idea to seal the brickwork to prevent moisture seeping through.
Brian

 

[flying haggis]

Ta chaps.




Just ordered the 2core SWA from superlec direct. a fair bit cheaper than TLC which I was surprised at. £20 saving alone in delivery! That's another £122 on the list.

any particular reason why you chose 2 core swa and not three core, i would have gone with three core which means you are not relying solely on the armour for the earth

 

[DBT85]

Ta chaps.




Just ordered the 2core SWA from superlec direct. a fair bit cheaper than TLC which I was surprised at. £20 saving alone in delivery! That's another £122 on the list.

any particular reason why you chose 2 core swa and not three core, i would have gone with three core which means you are not relying solely on the armour for the earth

I only have a TT earth (spike in the ground) being out in the sticks. So there won't be earth from the workshop to the house, the workshop will have its own spike for earth. This is what I expected to happen anyway and then confirmed by the electrician.

 

[DBT85]

All sides are now level and staked at every 1200mm. Just did that to get the level back to the hire place. This afternoon I'll finish staking so that there's only 600 mm between each. Then it's dpm and mesh in!

Taking an interest in your project, I'm reminded of a water/moisture ingress problem I had with my workshop. It is a log cabin style structure built up on a course of bricks on a concrete base, ie similar to yours. From your drawings I see that you are proposing to build your brickwork right on the edge of the concrete. If I had done that my problem would have been reduced but not eliminated so I'll tell the story:-
The brick course was built about 6" from the edge of the slab. The building timbers were laid directly on the bricks. After a year or so a few cracks developed in the brick mortar which allowed water ingress resulting in puddles on my workshop floor. This was a problem only on the SW facing wall subject to prevailing wind and rain. It was particularly alarming because I had put in a line of tool cupboards along that wall.
I tried various methods of sealing but to no avail. Eventually it was evident that the whole wall was suffering from the elements so drastic action was needed. This is the result:- Firstly I sealed the bricks to the slab with flexible plastic flashing. This was followed by cladding the entire wall with fibre shingles making sure they overlapped the flashing by a good margin. This system has been installed for about 4 years now and I've had no further problem.
With your design water falling off the walls will drain down the edge of the slab, but if cracks develop there may be a problem, although your 3 courses of bricks should be more stable than my single layer. It might be an idea to seal the brickwork to prevent moisture seeping through.
Brian

Thanks for the interest and the details of your problem Brian.

I can't say that anything about my design will stop it, it's all based on Mike's work. At a guess the 3 course brick and then 50mm block will help, plus the featheredge will kick out a fraction over the brickwork. There won't be anywhere for water to pool.

 

[MikeG.]

......There won't be anywhere for water to pool.

That's your answer....and why casting the slab edge accurately is really important.

Incidentally, it doesn't need any damage or cracking to the mortar for Yojevol's problem to occur. Mortar will always allow water through, even when perfect, so if there is pooled water sitting on a slab against a wall, you'll have water on the inside in no time flat.

 

[DBT85]

Today proved fruitful again but I am now stuck without assistance tomorrow. I just can't put that mesh down on my own without puncturing the dpm I don't think.

Formwork re-checked for levels, staked to 600mm and tops sawn off.

DPM unfolded and laid out, corners folded.

First bit of mesh moved but I just gave up without help. Hopefully tomorrow morning father in law can come up and give me a hand to get them down.

 

[Fidget]

That looks enormous doesn't it?
Bet you can't wait

 

[DBT85]

Looks like I'm going to be without a concrete poker

 

[MikeG.]

Damn. That's rather important with all that steel. Do what you can to find one.

 

[DBT85]

I've tried everywhere. Hss will let me have one from 9. But it won't get back here till 9.30 at the earliest. Too late?

Concrete due from 8

 

[MikeG.]

Why wouldn't that work? You don't need it until all the concrete is in the formwork.

 

[DBT85]

I dont know how long I've got to use the thing as I've never done it before. Will it still be of use some 1.5-2 hours after its poured?

Didn;t find out from my hire palce that they didn;t have one until 4:45 so loads of time to sort one.

 

[MikeG.]

It's not quite like that.....because your pour will take some time. You're using a dumper, aren't you? I'll bet it takes half an hour plus to do a lorry load with a dumper, and I bet you have 1+ loads, don't you. So it's going to take well over an hour just to get the concrete in the formwork. You'll then be pushing it roughly into place with forks. I reckon 9.30 will be about the time you'd want to be using it anyway. If you let the readymix company know the situation they might suggest wetting up the concrete a bit, which is fine so long as they also strengthen it, and this should mean that it should still be "pokable" by mid morning, even in this warm weather. As a bonus, I think it's going to be a bit cooler tomorrow, which will help. Poking the concrete will take 5 or 10 minutes, tops.

If you can't do it, then you are just going to have to belt the mesh with you forks, and give it a waggle too. It's not the same thing, of course......but don't sweat it. There's plenty of spare strength in that slab.

 

[DBT85]

It's not a ready mix it's mix on site with a 2 ton dumper.

 

[MikeG.]

You'll be fine. You'll find the guys doing the mixing are extremely helpful, and they'll make it work for you. I can't see any issues with poking it at 9.30.

 

[DBT85]

Ok I'll panic less.

I'll still try and get one from a bit nearer so its just here and ready. If the rest of the pour is done then I can always fill the dumper up before they do and hope there's enough in it to top the slab up after poking.