garage/workshop conversion: final questions

Hi,
As you know, I have been taking inspiration from previous posts here and I have:
painted my brick garage with bitumen paint put celotex against the walls and finally I am fixing plywood to protect the celotex from knocks and to give me something to fit shelves to.
One poster said that he had screwed through the plywood into the wall with long (4 inch?) screws and wall plugs. I was thinking of using hammer fixings, which are more or less the same thing aren't they: a big screw in a plastic plug. Do you think these will be strong enough. I don't want the plywood to fall in once I have loaded my shelves! Is it worth upgrading to through bolts or something meatier?
When I was pricing the plywood a couple of timber merchants raised their eyebrows when I said I would screw the shelves into the wood. I am sure that's what others here have done. Surely they don't need long screws into the wall as well?
Finally, I've quickly rollered some paint onto all sides and edges of the plywood to keep any water out. I only did one coat because I was eager to get on with the job. Do you think that will be sufficient or should I have given it a second coat to completely seal it?
TIA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No ventilation gap?

Depends how thick the ply, how heavy the shelves, what sort of brackets, how many screws,... It works for me with 18mm ply and light cupboards/shelves.
MBQ
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 14 Sep 2010 07:35:40 -0700 (PDT), Man at B&Q wrote:

I was wondering why the damp proof layer is on the cold side of the insulation.
--
Cheers
Dave.




Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
What thickness of insulation do you have?
If it is something like 20mm 25mm 30mm then look up "Rigifix" on Ebay. They are not cheap at about 0.80-1.00 each, but they do work ok.
Basically you have a long wallplug tube, then a steel sleeve which you allen-key screw into the tube, then a M6 (or M8) metric machine screw which screws into the sleeve. They work well, a pity they are not of German Fischer quality - but then they are ok and not priced like Fischer!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

50mm
I've just found them on ebay. Never heard of them before. Thanks for the suggestion.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Because it's a wall, not a roof, and also because it's not a habitable space.
Insulation goes on the warm side when you have damp humans breathing out in there. My small workshop walls are poor quality permeable blockwork and there's not much heavy breathing going on inside. The bitumen & rubber emulsion is on the walls to keep damp in the walls from evaporating inwards, more than it is to be a vapour barrier from the inside into the insulation. I also used polystyrene rather than rockwool to avoid any problems I might have.
The big workshop roof will be rockwool, and that will have a vapour barrier on the warm side, with a vented space on the cold side.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

does celotex absorb much then?
Jim K
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 15/09/2010 16:51, Jim K wrote:

Not much - and much of it is foiled on both sides, so if you tape the joints with ali tape there is no further need for a vapour barrier.
--
Cheers,

John.

/=================================================================\
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 14 Sep 2010 22:45:57 +0100 (BST), "Dave Liquorice"

I thought it was because the damp we're keeping out is damp from outside rather than damp from inside and besides, if we had to paint the outside wall with bitumen it would look ugly! Perhaps I put it on too thickly but I got ugly runs everywhere. Is that my poor technique or is it the same for everyone?
Thanks to Andy's post I now understand why; I think I was thinking along the same lines. And in answer to Jim, I'm hoping the foil of the celotex will act as a barrier if needed (the joins are foil taped btw).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

yup I'm sure you are right ;>)
Just probing Liquorice's 'understanding' .... but no reply from him ;>))
Cheers Jim K
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Fred wrote:

Exactly what brackets and screws do you propose into what thickness of plywood? I can't see that you are going to be able to support any significant load in this way.
Chris
--
Chris J Dixon Nottingham UK
snipped-for-privacy@cdixon.me.uk
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 14/09/2010 15:24, Fred wrote:

Twas me... I used 5 1/4" screws IIRC.

Probably - although they have more "plug" than you need (you only need the plug on the end of the screw in the masonry. The 2.5" of screw through wood and insulation does not need to be in a plug.

Not really. You can always screw critical shelves to the masonry as well with the same long screws. For my heavy shelving (floor to ceiling, that carries all the tools in cases and tool boxes etc) I used spur type metal rails that sit on the floor and are fixed through the cladding to the masonry. That way there is no real load on the cladding.
However, for all the others I used similar spur rails - but just fixed to the cladding, and not full height. There is no sign of it causing a problem.

I have done both - as above.

One will be adequate I would have thought. Especially if its WBP ply - its not really susceptible to water ingress.
--
Cheers,

John.

/=================================================================\
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 14 Sep 2010 15:43:48 +0100, John Rumm
Crickey, I don't think I've ever seen any over 4 inches. Where did you get those? Do they need to be stainless to prevent rusting or will they be dry enough that a cheaper variety might do?

I thought a hammer fixing would simplify things as I would drill a hole in the wood and just push the fixing through. If I used separate plugs and screws, I would have to move the wood and insulation after drilling to get to the holes to plug them and that would be a hassle. I did wonder whether I could push the plugs through in situ using a wire coat hanger or something similar but that sounds like it might be more trouble than it's worth. What did you do?
I have used hammer fixings with great success before. I've even used frame fixings when I bought the wrong ones by mistake and didn't notice ;)
They say hammer fixings use stronger screws to withstand the hammering but the frame fixings didn't seem to mind! I wonder whether the screws are really that different? They don't look it.
That said, this time I have had a lot of trouble with hammer fixings bending when hammered. I wonder if I would have had more success if I had screwed them in? I guess that's what you are supposed to do with the frame fixings?
I guess they must be pretty strong since they are used to hold windows and door frames. If a window if glazed or a heavy door is hung both of these must take quite a weight, or perhaps they don't? Perhaps the window sill and the floor take some of the weight, reducing the load on the fixing?

Yes, I was thinking of using the same type of rails but I hadn't realised you screwed through the board into the wall. I thought they just went into the wood. I'm not expecting anything particularly heavy but lots of little weights will add up.

That's reassuring, thanks.

Oh. perhaps I made more work for myself then. Still it's better to have done too much rather than not enough. I only used a primer to seal the surface and used a roller for speed. I noticed one or two patches on one or two panels where the coverage didn't seem complete. I thought I had applied it too thinly. I was worried this would need a recoat but it seems it may be ok after all then.
I was told it was wbp but there was no marking on it to say so. No markings at all. I did a "plywood" post about it but its an orphan post at the moment waiting for a reply, lol.
Thanks again.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

The screws aren't very strong. I used them to hold a gate post to a wall and the screws broke off in the final tightening. The plastic sleeve still holds the gate post in place though, and it's now been up for a number of years.
S
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 15/09/2010 21:34, Fred wrote:

Screwfix ;-)
http://www.screwfix.com/prods/16127/Screws/Interior-Wood-Screws/Quicksilver-Screws/Countersunk-Prodrive/Quicksilver-Countersunk-Prodrive-12-x-5-1-8-Pack-of-50
(galvanised, so rusting is not a problem)

Quite possibly...
You can get some that are 100% nylon as well to prevent the screw acting as a cold bridge if you want to be really anal!

Na, simple technique: get a longish Bosch multimaterial 7mm bit. Slap insulation against wall - quick squirt of expanding foam to tack in place if you want. Slap board against it. Drill right through the lot and into the wall. Take screw, and wind brown masonry plug a couple of turns onto the end. Stuff in hole, tap with hammer until only 2 - 2.5" is left sticking out, drive home with powered screwdriver of choice.
(BTW, the using the screw to tap in a wall plug is a counter intuitive technique that I did not think would work when first told about it, but it actually works very well!)
I did six screws per sheet (8x4')

See above (sorry must read further before writing!)

Have you seen a 12 gauge 5" screw before? They are "adequate" ;-)

Window a door frames don't really need much fixing - the pull on the stiles is resisted by the top/bottom of the frame. You can just fix them with expanding foam (as is commonly done on highly insulated houses where the only thing to fix to is a plastic and foam cavity closer)

Well I have a set of six shelves - floor to ceiling that also go round the corner a bit. Held up on three sets of uprights. These are all about 500mm deep. The bottom shelf has three tool boxes (electrical, network/phone, and one full of misc crap!), Jigsaw, SDS Drill, Combi Drill in cases, plus a couple of other power tools in boxes. The rest have similar levels of stuff on them!

Those were using 1.2m ish rails - so the load is spread over half the height of the ply, and that is in turn held on at least 4 screws.

If its over foil faced board I can't see it being a problem. (I painted mine with magnolia emulsion - but that was to make the workshop bright and light and not as a damp proofing measure!)

Take a small offcut and soak it. Leave it outside for a couple of days. If it turns into a de-laminated mess then its not WBP. If its still mostly in one bit it is! (note the surface can be a bit flakey on the cheap shuttering ply - but its still WBP)
--
Cheers,

John.

/=================================================================\
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 15 Sep 2010 22:52:59 +0100, John Rumm

Well I never expected that.
I prefer tool station because of the free delivery on orders over ten pounds. It's not often I order the 50 required for free delivery from Screwfix. Sadly TS only go up to screws of 4 inches.
I was expecting the link to go to some exotic decking screw or something, not a "plain" quicksilver screw!
The big screw sizes seem a bit peculiar in imperial measurements: 4 1/3" and 5 1/4". I did wonder why there wasn't a 5 inch but it occurred to me that in metric these probably make more sense. I think 5 1/4 is about 130mm, which would explain that one. I haven't bothered to work out 4 1/3"

Yes, I think I've seen them in the catalogue once but how strong is nylon? I wouldn't expect plastic to be as strong as steel, is it? I know screws being cold bridges were mentioned in an old thread but really, how much heat will a 10mm screw heat suck out of the room? I am hoping not much.

I wonder why they do make them so big?

7mm seems to be a funny size. SF only sells 100mm and 150mm bits, whereas the more common 6mm and 8mm bits are available in longer lengths. Still, I suppose the 150mm would just about do the trick, unless I could use an 8mm plug with an 8mm bit.

Thanks for the tip. I never expected that.

That's what I was thinking: one in each corner and two in the middle of each long edge.

I am sure it would be easier for the manufacturer to just use one screw in both fixings. I can't really see the difference expect the frame fixing has two lugs at the end. Do they really make that much difference?
Thanks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Because they are frame fixings! The idea being not that 'you hammer them in' but that you drill through the frame with it in place rather than put a rawplug in and then try to line it up after putting the frame in. The bulk of the plug lines the hole you have made in the frame, or it would not be very fixed and might wobble about.
S

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 16 Sep 2010 18:00:46 +0100, "Spamlet"

I was thinking that if screwed tight the pressure of the screw head would hold the frame in place with or without a big "plug" but yes, with the long plug it would be even more secure. Thanks for the explanation.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

YW,
As I mentioned somewhere else, I think the screw itself is just to flare the base of the plug out and anchor the frame fixing, which is really the extended plastic tube. I found that the screws themselves were not very strong, when I used these fixings to hold a gatepost to a wall, for a small gate I'd made. Thinking they needed to be tight, I used my big screwdriver, and was surprised when the head broke straight off one of the screws. The flared plastic part has held the post firm for a number of years now, none the less.
So I would say that the thing to be careful of when using this type of fixing, is not to get the screws particularly tight, but to *make sure you use the right drill to the right depth*, so that you do not have to put too much torque on the screw. It just needs to sit neatly in the flared end of the fixing: not try to push the plastic in - which can't be done, if you think about it, because the other end of the screw has fixed it in the wall, and further tightening is trying to compress the whole length of the plastic tube. Conceivably, overtightning could split the frame, if your screw was strong enough to compress the plastic: in my case I was probably lucky that the screw broke first: possibly this was a designed-in failsafe to prevent splitting.
Hope the shelves went in allright: it's nice to have everything tidy when you are working.
Mind you, shelves are always full right up, no matter what you do. In a fit of desperation for tidiness, I shelved the whole of one wall of SWMBO's office while she was away one weekend, and cleared the floor that had been piled high with boxes of files for years. The relief only lasted a few weeks, and now we only have one small cluttered footpath between the door and the pc, and can't get near the long filled shelves without mountaineering gear, and getting roped in to get over what is supposed to be the spare bed!
I'm sure you will fare better! ;-)
S
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 16/09/2010 10:41, Fred wrote:

In reality they will lose little of relevance. The Nylon versions are usually heavy (i.e. 16mm diameter) beasties for fitting cladding and render mesh on the outside of houses. These the significant thickness of steel and the large mesh (i.e. renderable) head may make more difference to the heat conducted.

7mm diameter is the usual recommended size to match the brown plugs. They also match the screws nicely.
(note the SF description of the screws is slightly wrong - IIRC the top of the shank is not threaded - there is a plain bit)
i.e. make sure you get this one:
http://www.screwfix.com/prods/71772/Drill-Bits/Masonry-Drill-Bits/Multi-Purpose-Drill-Bits/Bosch-Multipurpose-Drill-Bit-7-x-150mm
(6" long, and not the smaller 4" one)

You could - but I found 150mm was plenty with 62mm of cladding (wood and foam).
Just be careful if using long bits on a single skin wall to not go right through!

No, me neither. Having derided the suggestion on the grounds I thought it would just drive the screw into the plug but not move the plug, I had to eat some humble pie!

Yup.
Frame fixings seem to come in a variety of types and styles. Usually their main distinguishing feature is they are long - longer than you need in this case I expect. I have not tried the hammer in type - they may well work fine.
--
Cheers,

John.

/=================================================================\
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.