• Hi all and welcome to TheWoodHaven2 brought into the 21st Century, kicking and screaming! We all have Alasdair to thank for the vast bulk of the heavy lifting to get us here, no more so than me because he's taken away a huge burden of responsibility from my shoulders and brought us to this new shiny home, with all your previous content (hopefully) still intact! Please peruse and feed back. There is still plenty to do, like changing the colour scheme, adding the banner graphic, tweaking the odd setting here and there so I have added a new thread in the 'Technical Issues, Bugs and Feature Requests' forum for you to add any issues you find, any missing settings or just anything you'd like to see added/removed from the feature set that Xenforo offers. We will get to everything over the coming weeks so please be patient, but add anything at all to the thread I mention above and we promise to get to them over the next few days/weeks/months. In the meantime, please enjoy!

Mike's Workshop Build (Extension & slates)

I'd miss read the notes and assume the dotted line to be DPM. My error. Apologies

I presume there will be something by way of a DPC under the sole plate and then down over the arris to stop any moisture wicking up through the soft brick into the timber?

Bob
 
Yes, omitted in error. The sole plate will sit on a 150mm DPC which goes flat on top of the bricks, and under the arris. The secondary DPC, over the arris, will lap over the top of the primary DPC. The former is to prevent rising moisture, the latter to help remove any falling moisture from leakage through the boarding, or, unlikely but possible, interstitial condensation within the wall.
 
Something else not shown is that the sole plate may well be bedded on mortar, as the bricks I am using are rather varied in shape. It will be difficult to achieve any sort of flat surface on top of the plinth on which the sole plate would sit flat, without a mortar bed. The alternative is to bed the plate on silicon. I specify this for houses, but it may be overkill for a workshop.
 
I'm intrigued by the silicone bedding Mike. Is that because it will remain resilient whereas mortar might crack with the construction work when building upwards?

I've certainly had bedding mortar crack at wall plate level when starting on the roofing a bit too quickly after bedding the wall plate.

Bob
 
In a house it is to ensure air-tightness at a very vulnerable point in the fabric of the building. Take the nozzle off the silicon tube, because you're going to want lots of the stuff! A low modulous silicon will keep a good grip even if the timber moves quite a bit. With an oak plate, I have specified a 2 rebates with a strip of those expanding tapes, for the same purpose.
 
Mike your pictures are not as good as they used to be :D
This is one you prepared quite a few years back that I have safely tucked away for future use and has a little more detail.


Hope you don't mind me posting
 
Not at all, Andy. It's only minor variations from that old scheme that I am proposing......mainly because I don't like to see boarding sticking out so far from the plinth. I also am screwing the straps to the base, rather than casting them in (because of the power-float, and the general nuisance of straps sticking out of concrete). Other than that, much the same.
 
Mike

I like the amendment to the plinth detail versus the prior version to avoid an overhang by the cladding. One question though, the new version of the plinth shows a 50mm block, are these a relatively standard item? I have only ever seen 100mm wide contrete blocks - but then I rarely stray further afield than Wickes!

Terry.
 
Wizard9999":2kwcnzk3 said:
Mike

I like the amendment to the plinth detail versus the prior version to avoid an overhang by the cladding. One question though, the new version of the plinth shows a 50mm block, are these a relatively standard item? I have only ever seen 100mm wide contrete blocks - but then I rarely stray further afield than Wickes!

Terry.
Click to expand...

Absolutely standard at a Builder's Merchant, Terry. I suspect that even Wickes would be able to get them in for you, but a decent Builder's merchant should keep them in stock.

Mike
 
Mike

Thanks for the reply on blocks.

One more question if I may. In terms of design I see you have a couple of hatches to allow for very long lengths of timber to be worked on, but only one window. I would have assumed that a lot of natural light would be a benefit so wondered why so few windows and why not simply make the hatches into windows? Is it a security issue?

Terry.
 
Windows and hatches are at very different levels, but fundamentally, it is security and cost. I live in an isolated rural dwelling, and although the chances of burglary are slender, the risks are too high to ignore. The window will have some sort of grill behind it, or shutter over it, for security, and having more than one window will just increase my work, costs, and my risks. No rooflights ("Velux") for the same reason.

Mike
 
I got a few hours at it this afternoon, and finished cleaning up in the dark. The photos are a little behind where I am, but I ran out of light for photography.

First, I made a jig. Woodwork!!! :eusa-dance: There are lots of half bricks in the bond I am using, and it seems easier to bulk cut them with an angle grinder than try and snap each header as I am working. I then spent an hour cutting a whole lot of bricks.
sboYhLD.png

Then I worked out the gauge. Frankly, I worked it out on computer first, but I like to site-check these things:
CvY2u8i.png

Then I started building corners. These are pre-brushing, so the pointing looks an awful lot better than this:
Ks3yFqo.png

I'm a really slow bricklayer, but even so, I should finish the brickwork in 3 or 4 hours work. I went around 3 or 4 different merchants before I found the right coloured sand: most are too dark, and even this could be whiter, but it won't be too bad when it's dry. Before I go any further, I shall have to determine exactly what I am doing regarding doors, because I have to leave a hole for them.

The concrete finish is an absolute joy. I am really pleased to have something so smooth, and level. Sweeping up is such a pleasure!
 
Aesthetics only, Terry. I really dislike stretcher bond brickwork, and use Flemish or English garden bond whenever I can. Flemish bond (and most other bonds), originated with 9" brickwork, where the headers held the 2 faces together, like through-stones do in a dry stone wall. Stretcher bond brickwork has really only seen widespread use since cavities started to be built into external walls in the middle of last century.

-

More photos tomorrow, but the brickwork is nearly complete. Tomorrow I'll be putting the straps in, and doing the 50mm blockwork.
 
Mike, are you doing all the mixing and laying all by yourself?

Laying bricks low down like that really kills the back.

Cheers
Phil
 
Yes, all by myself. Frankly, uncomfortable as it was laying bricks by my ankles, it was only about 10 hours work altogether so I gritted my teeth and got on with it. My back is a bit stiff, but not too bad.

Photos later.
 
Mike G":hzfltvyk said:
More photos tomorrow, but the brickwork is nearly complete. Tomorrow I'll be putting the straps in, and doing the 50mm blockwork.
Click to expand...

Really looking forward to the photos Mike as I am really keen to see how the whole 'strap thing' works; I plan to shamelessly copy your technique on my own build. Hope you have a productive day!

Wizard9999.
 
The straps won't be on the next photos, which will be brickwork only. I have decided to do the straps just under the blocks, so they (the straps) will be the next job.

My last workshop, built in a similar manner (albeit with the straps set into the concrete, and a 4" rather than a 6" wide plinth), showed me something quite interesting. In clearing it recently, I discovered that I had forgotten to secure the straps to the wall plate. In other words, the studwork, and thus everything above the plinth and DPC, was sitting in place through gravity alone! It hadn't moved a millimetre in the 18 years it has stood there in all weather. The many 100 mph gales we've had had no effect on it whatsoever. Now, I'm not about to omit straps altogether from my new building in spite of that experience, but I am going to be using Compriband instead of the 5mm thick straps you get from builder's merchants.

As for copying me...........that's the whole point of posting my drawings and doing this thread. If I can get a few people to put their new sheds up on a low plinth, then my good deed is done. As I've said many a time.........timber building without a plinth = temporary shed. Timber building with a plinth = workshop.
 
Here are the latest photos, showing the completed brickwork. Despite being rather a slow bricklayer I am quite pleased with how this looks.

YcVFw3N.png
gdbDlFe.png
zHWLWaf.png

The reason for 3 courses of bricks, rather than the 2 in my original sketch scheme from years back on UKW (where?) is that I will be backing this up with 50mm blockwork, which is 3 courses of bricks high unless you want to spend hours and hours cutting blocks.

Next job is straps, then blockwork, then the timber frame wood arrives on Monday. Things should start to happen quite quickly then.
 
Mike,

Always an exciting time when building start getting out of the ground.
I can't quite see how your damproofing is going to work. I assume the black poly is the under slab DPM, so what is to stop moisture getting into the slab via the external brickwork and the vertical edge of the slab?

Apologies if this is a dumb question

Bob
 
Looking really nice Mike! :text-bravo:

I think three courses will look really good, only two courses would run the risk of looking a bit mean, IMHO.

Wizard9999.
 
It isn't a dumb question at all, Bob. In fact, it is a very important one.

The concrete stays dry because of the DPM underneath, and because the upper edge of the slab is above ground level, enabling it to dry with air movement. I will be cutting the polythene back to where it turns up the edge of the slab. If I were to leave the polythene up the edge of the slab and tuck it under the brickwork, UV would destroy it in no time flat. Obviously things would be very different if the slab were below ground level, but some of mine (at the back) is about 9 inches above ground level.

We're talking about 160 to 350mm of C35 concrete here, and whilst I wouldn't advocate it, it would probably stay dry if there were no DPM at all. There is no way of having the DPM stop at ground level, even if you wanted it to. The DPC will be on top of the plinth, under the timber, and this is mainly because bricks absorb moisture then release it slowly, thus can remain damp for some while.

The proof of this particular pudding is in the eating, and the way to test for moisture in a slab is to put a piece of plastic on top of it for a day of two, and see if a dark patch emerges. Well, I did this with my previous workshop built to this same design, and it was dry as a bone.
 
Wizard9999":3fbk3vyb said:
Looking really nice Mike! :text-bravo:

I think three courses will look really good, only two courses would run the risk of looking a bit mean, IMHO.

Wizard9999.
Click to expand...

Thanks Terry, and you're right. However, I'm conscious that some following on here will be looking to build their workshop as frugally as possible, and 2 bricks is the bare minimum to ensure a plinth works.
 
Mike G":2dxe8rgy said:
It isn't a dumb question at all, Bob. In fact, it is a very important one.

The concrete stays dry because of the DPM underneath, and because the upper edge of the slab is above ground level, enabling it to dry with air movement. I will be cutting the polythene back to where it turns up the edge of the slab. If I were to leave the polythene up the edge of the slab and tuck it under the brickwork, UV would destroy it in no time flat. Obviously things would be very different if the slab were below ground level, but some of mine (at the back) is about 9 inches above ground level.

We're talking about 160 to 350mm of C35 concrete here, and whilst I wouldn't advocate it, it would probably stay dry if there were no DPM at all. There is no way of having the DPM stop at ground level, even if you wanted it to. The DPC will be on top of the plinth, under the timber, and this is mainly because bricks absorb moisture then release it slowly, thus can remain damp for some while.

The proof of this particular pudding is in the eating, and the way to test for moisture in a slab is to put a piece of plastic on top of it for a day of two, and see if a dark patch emerges. Well, I did this with my previous workshop built to this same design, and it was dry as a bone.
Click to expand...

Ok Thanks Mike I understand now but a couple of things come to mind. It will be important to keep grass/weed growth away from the plinth and any cupboards or other restrictions to letting the slab breathe, need to be kept away from the walls.

Bob
 
Rod":3tm60z2g said:
What sort of bricks are they - they look quite "soft"?

Rod
Click to expand...

They're a soft red called Renaissance, made by Terca (now called Wienerberger).http://www.cornishlime.co.uk/stores/product-info.php?auto=220&cat=2&sub=33 I have used their Olde Essex from the same range for many years, but wanted something that looked just old, without looking reclaimed. These are designed to look hand-made, but are a machine made brick with lots of variation, and no straight lines. They're surprisingly cheap, too, and are a stock item at most of my local Builder's Merchants. I shall be using them for the house extension, too, as I am impressed with them.
 
9fingers":1yxm43gj said:
Ok Thanks Mike I understand now but a couple of things come to mind. It will be important to keep grass/weed growth away from the plinth
Click to expand...
Correct, although soil level is more important than plant growth.

9fingers":1yxm43gj said:
and any cupboards or other restrictions to letting the slab breathe, need to be kept away from the walls.
Click to expand...

No, it is only the outside edges of the slab that need air to them. Bear in mind that moisture can only get in from the outside edge, and it just doesn't penetrate 6 inches in to the concrete, (and up) to clear the underside of the walls. The slab inside is not part of the ventilated-slab scheme, and you could perfectly well put a floating floor on this slab without running into trouble with trapped moisture.
 
I'm not "putting up with your questions", Bob. They're astute, and the sort of detail which keeps me awake at night. All of your questions I have asked myself.

-

Just as a caveat, in case anyone really needs it: this construction technique is for outbuildings only. It is NEVER to be used for an extension of a house. Things get very different there, and building straight off a flat slab would almost never happen.
 
Mike G":el15jjr0 said:
No, it is only the outside edges of the slab that need air to them. Bear in mind that moisture can only get in from the outside edge, and it just doesn't penetrate 6 inches in to the concrete, (and up) to clear the underside of the walls. The slab inside is not part of the ventilated-slab scheme, and you could perfectly well put a floating floor on this slab without running into trouble with trapped moisture.
Click to expand...

Mike

A couple of questions if I may. You say that the outside edge needs air to it and if I read correctly the slab is anywhere between 160 and 350mm thick. How much of it needs to be above surrounding ground level to allow sufficient exposure to the air? Is there an absolute minimum, e.g. 50mm, or is it proportionate, e.g. top 20% of slab.

As I need to stay under 2.5m high as I will be within 2m of my boundary every 1mm of exposed slab is a 1mm less headroom. So I will need to minimise the amount of slab above ground level, but want the 'system' to work. Would an approach whereby a trench is dug around the outside of the slab and filled with gravel provide sufficient air circulation even if the top of the slab is level with ground level?

Thanks in advance,
Terry.
 
Well, if you are going to have the slab at ground level, Terry, you can wrap the polythene around the the edge of the slab and under the brickwork. Then loose fill such as shingle around the perimeter would be ideal, especially if you can lay a French drain in it too. If you are exposing the edge to the air, then I suggest 50mm as a minimum.

Headroom needn't be much of an issue, though, however low the building, because you needn't have any joists in the ceiling/ roof.

BTW, my slab is 350 thick in one location because there was some horrible loose made-up ground under one corner. In reasonable soil I would have made the slab 150 thick, and maybe thickened up the edges to 200.
 
TheTiddles":254a9277 said:
Are you still in the new (old) house that you designed and I saw in Suffolk years ago?

Aidan
Click to expand...

No, I've moved to an old old house. A hovel, but with loads of potential, and a big garden.
 
I did the straps this morning. I had intended to screw them to the concrete, but 1 minute of drilling which achieved a depth of about 10mm suggested that this was not going to work. That concrete is hard! So I screwed them to the bricks instead. I will then lay the blocks on top of them, fold them up and over the sole plate, and screw them in place.

Firband straps (I think that's what they're called..........rolls of galvanised mild steel perforated straps) at max 2000 centres, and adjacent to openings. As it happened, I cut one or two too many, so mine ended up at max 1800 centres.

E27SNkM.png

xCOMjp8.png
 
That looks much nicer strip than I've used in the past. Mine were ready formed as an L shape and the edges were rolled and so made them much more difficult to form a tight bend without trimming away the rolled edge, exposing the raw steel etc.

I was using them in the roof and hidden from view so it did not matter. Buying it on a roll as 'builders Meccano' seems much better.

Bob
 
Sounds like you were using the 5mm straps typically sold 100x900 or so (ie c.20x5 in section, and L-shaped, with a leg 100 long, and another leg c.900 long). They're used, for instance, for holding a roof plate down onto blockwork in a house. This stuff is much less beefy, maybe 1mm thick, and sold in rolls. Mine is old stock: I've probably had it 15 years.
 
Mike G":ia37gqw8 said:
Sounds like you were using the 5mm straps typically sold 100x900 or so (ie c.20x5 in section, and L-shaped, with a leg 100 long, and another leg c.900 long). They're used, for instance, for holding a roof plate down onto blockwork in a house. This stuff is much less beefy, maybe 1mm thick, and sold in rolls. Mine is old stock: I've probably had it 15 years.
Click to expand...

Exactly that Mike and to be fair, wall plate location was my application.

Bob
 
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