Yep... It's another workshop. Guttering

[mindthatwhatouch]

So I have finally got started on the workshop. Block built (needs to be non combustable) 7m x just under 5m pitched roof is what I have planning permission for. The long side walls to be built in block with gable end above garage door in timber, gable end garden will also be timber clad stud wall with the cladding extending over the ugly blocks.

In the future may well clad the lot or have it rendered.

I have cleared site and started digging footings but have a couple of decisions to make and would appreciate your advice. learnt alot already from this site but need second opinions on several things.
Yes I know photos are compulsory, I will upload some, don't worry the speed that I work you are not likely to miss anything.

1. Foundations (sketch attached. hopefully) footings and 3 courses of blocks to bring me up to slab level, there is a height difference between mine and neighbours. Structural engineer has advised it is ok to infill with dry fill between two walls but should I line the blocks with some form of damp proofing to keep the worst of the moisture away, ie a basement plastic lining type material?

2. I can of course step down the DPC once I am past the higher part, but is there any problems with keeping the DPC up so high?

3. Slab, I would like to insulate the slab a little (under and around the perimeter) to keep the damp and cold at bay. will 25mm of jablite make much difference? can I use expanded polystyrene below the slab? and what do I do at the garage door end, or just leave the vertical piece of insulation out here and accept the cold bridge?

I shall attempt to attach the sketch, more questions to follow.

Thanks in advance

 

[RobinBHM]

Hi welcome to the forum, plenty of advise to here for workshop builds

7m x 5m is certainly a palatial home workshop, at least by my standards!

If you want to render the outside, think carefully about dpc position. Conventionally a bell cast drip bead is positioned at the dpc course and the render finishes at this point. Often the masonry is brick below this.

If you are doing the work yourself, I would have thought more than 25mm insulation would be worthwhile. Having said that a workshop isnt heated much so maybe the concrte mass will always feel cold even if it insulated and perhaps a timber floor would better. Id be interested to see what others think.

 

[mindthatwhatouch]

A little more.

Attached sketch of the general layout to try to make things clearer.

Don't really want to insulate the interior because then I would need to line it with OSB/Ply.
Cladding on gable ends. Is it ok to place Tyvek (or similar, any recommendations?) straight against the blocks or would it need battening out first.
Trying to keep the cold and damp out, my first choice would be to build in timber but needs to be substantially non combustable.

general layout

 

[mindthatwhatouch]

And finally a couple of pics.
Start of the excavations before the storms turned it into a mud bath.
Oh the joys of digging in October.....

 

[Wizard9999]

Trying to keep the cold and damp out, my first choice would be to build in timber but needs to be substantially non combustable.

Maybe timber is an option. On Steve Maskery's mega build thread (a sticky in General) he has said he is within a metre of the boundary, which I presume is why you need to be "substantially non-combustible", but his workshop is built of timber. A while back there was some discussion about him looking into fire resistant treatment for the cladding, but I don't think that discussion ever ended before the thread moved in a different direction. I know people will say different council building regs depts. look at things differently, but why don't you asking him what he is doing to comply with building regs. Then maybe you can follow suit and stil use timber.

Terry.

 

[mindthatwhatouch]

Robin: good point about the drip bead. Ta

Terry: I shall find out what advice Steve Maskery has to offer.

The digging continues......
almost half way round.

Tony

 

[Alex_E]

25mm insulation is nothing In a floor. 100mm is pretty standard in most building work these days?! And that's celotex or similar as well! Also why not do a bulk filled footing saves all the hastle trying to lay that far into the ground! Just stop it one course below ground instead.

 

[mindthatwhatouch]

Hi Alex.
I appreciate that 100mm or more will go into a domestic build but this is a garage. I have yet to find out what difference a small amount on insulation will make or even if its a good idea to lay it below the slab.
Perimeter insulation will make a difference and it separates the slab from the walls so this will go in, regardless. Celotex, Jablite etc all do products suitable for laying below a slab but it is all geared towards domestic interiors, i.e. foot traffic,

The reason I am not using a trenchfill foundation is twofold.
1. I can't dig a neat trench that depth.
2. the extra cost of the concrete.

On a plus note its all dug out now so hoping to get footings poured next week when I can get a couple of mates round to assist. Done my best to cover the trenches in a (probably futile) attempt to keep some of the water out.

Tony

 

[flying haggis]

:nopics:

 

[mindthatwhatouch]

Well it was all dug out, then more rain....
spent today pumping and using aquavac to get water out, then tidied up the loose soft bottom of trench, footings pour tomorrow.
Pics of my own personal somme re enactment site to follow.

Re floor slab. I have decided on polystyrene for the perimeter but still cannot find if its advisable to put it under the slab.
Any ideas people?

Also do I go for mesh in the slab or more concrete, no mesh maybe with fibres???

 

[Wizard9999]

Well it was all dug out, then more rain....
spent today pumping and using aquavac to get water out, then tidied up the loose soft bottom of trench, footings pour tomorrow.
Pics of my own personal somme re enactment site to follow.

Re floor slab. I have decided on polystyrene for the perimeter but still cannot find if its advisable to put it under the slab.
Any ideas people?

Also do I go for mesh in the slab or more concrete, no mesh maybe with fibres???

Sounds like we may be at a similar stage, I have just finished getting hardcore and sand for blinding between hardcore and DPM in place. I'm no builder or engineer, but I am putting steel in mine because I am building very close to two large oak trees, so I have advised there is likely to be movement in the slab. Hard to answer the question re "more concrete" without knowing how much you already intend to pour. I have been told that 150mm is really a minimum for the slab, but mine will be anywhere between 150 and 300mm as it deepens on the side closer to the trees.

If I understand correctly the insulation can go either below or above the slab, but on top is more common. This is certainly what is shown in the definitive Mike G shed thread that is 'stickied'.

Terry.

 

[mindthatwhatouch]

Well after a couple of hours hard work the footings are in.
A few pics pre footings going in.

Think I need to tidy the site a bit

The wooden chute was reasonably successful to save some shovelling.

Wizard9999, Appreciate the insulation on top of the slab is more normal but I will be keeping the floor as concrete, certainly for the foreseeable future.

Blocks coming Monday

 

[mindthatwhatouch]

The Bombsite

Bit of tidying yesterday, pumped out water moved some blocks, rain stopped play.

 

[mindthatwhatouch]

Right then decision time.
150mm slab with steel mesh reinforcement.
Probably (unless someone advises me different) 50mm of EPS100 below slab, above the DPM.
Perimeter insulation 25mm.
Unsure how to deal with the DPM at the doorway.
Three courses of blocks brings me up to slab level.
Planning to have 2 courses of blocks below the doorway opening and run the slab over the top of them.
Do I wrap the the DPM up on the outside of the slab level with the outside of the wall?

Could really do with some advice to see if I am heading in right direction.
Hopefully blocks going in over next couple of days.

edit to add sketch:

 

[John15]

I can't open the pics

John

 

[Hobbyshop]

I can't see the earlier images but the layout of the DPM in the last picture looks strange. It appears to be below ground level.
I believe that DPM should normally finish at least 4 inches above grade on the outside walls.
Is there a reason why you have the top of your slab set at grade level?
Have you seen Mike Garnham's thread on design for a shed/workshop: https://www.ukworkshop.co.uk/forums/build-a-shed-mike-s-way-t39389.html

 

[mindthatwhatouch]

Sorry its a bad drawing.
The DPM will continue up the wall and lap in with the DPC.
That drawing was a cross section through the garage door opening.

No idea why people cant see the earlier pics! is there an alternative to imageshack?

 

[mindthatwhatouch]

John/Hobbyshop.
Hopefully you can see the pics now?????

Hobbyshop. Yes I have seen the excellent.. build a shed Mikes way post.
Just wish I had the option of using timber.

Not a very good couple of days, progress is painfully slow due to the rain...

 

[RobinBHM]

There isnt any reason why you cant put the insulation below the oversite, extensions can be constructed this way. The issue though is that there is then more thermal mass to be heated, so I dont think it generally done.

I would think 150mm of oversite concrete would be strong enough, unless your machinery is going to be cast iron Wadkin!

 

[John15]

Mindthatwatouch,

Many thanks for doing whatever you did with the pics - seeing them loud and clear now.

Good luck with your workshop build. Mine is a much simpler effort - a timber shed structure with a suspended floor.

John