# Build thread- My concrete workshop. Pg4 Bench built.



## PAUL_TDI (16 Aug 2013)

I've been browsing forums trying to search for insulation advice for my concrete prefab workshop but whatever I read raises question so thought I better join a forum and this seems like a fairly busy one with solid info.

So moved into my new house on 1st June and I had compromised on buying a house without a garage as long as it had a garden big enough to build a workshop.

Once the house was sorted I started work...






Base dug out to 6" throughout and DPM was laid before concrete was poured.

I had the ferns cut before workshop was installed






Then voila!





















It's a 16'6"x9' with 30" steel door and UPVC throughout, I wanted minimal upkeep so didn't want to need to treat wood regularly.

Insulation wise I was planning on a basic stud work wall around the inside with 2x2 as to not take too much space, the most I'll have directly on the wall are hand tool hangers and those plastic box racks. Then fill the void with sheet polystyrene.

Much the same on the roof aswell, just using a thinner ply to board it out.

My main question is what kind of ventilation should I leave into the insulation space?

I'm using Thomson water seal on the outside and was going to coat the inside too to reduce ingress damp(?)

I was originally thinking of using celotex/kingspan originally but unless some comes up dirt cheap then it's too expensive.

Comments and advice much appreciated!


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## PAUL_TDI (16 Aug 2013)

Thats annoying, how comes I can't post pictures via PhotoBucket?


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## PAUL_TDI (16 Aug 2013)

Whoops, suppose I should of read the rules first.


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## longinthetooth (16 Aug 2013)

Diminishing returns with insulation if you can't insulate what looks like a steel door? Any heat you introduced would just 'urinate' out through that, rendering any other insul. relatively pointless.

I'm assuming that you intend a heat source, even if intermittent?

Following yr studwork idea, I think you should leave a 25mm gap between that & the ribs of the wall panels so that there's a 25mm gap along the internal eaves behing the top of the studwork. This is to provide enough airflow esp since you have no air ingress at slab level. The other thing is to have an internal face that restricts the passage of moisture into the studwork layer. I can expand on that if needed. I'd also use treated wood for the studs and especially their soleplate.


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## PAUL_TDI (16 Aug 2013)

It's only a single sking steel door so was planning on attaching some baattern, insulating and boarding that too.

Would that surfice?

I'm not looking to make it super toastie but merely try and combat the dreaded damp of concrete prefabs, plus make walls I'm able to drill into and mount smaller items too.


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## longinthetooth (16 Aug 2013)

Yes you could replace the latch spindle with a longer one and the lock cylinder with one that was longer on one side (assymetrical) - look up some catalogues on-line for available lengths ...

Is doorframe steel also? Hellish detailing!


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## PAUL_TDI (16 Aug 2013)

Yes door frame is also steel, I wanted fairly good security and this was the best choice away from wood the company offered. It's a Hormann door and frame.


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## PAUL_TDI (16 Aug 2013)

Ah just read your edited iniatial post...

Yes I was planning on a oil radiator on a stat/timer to help. Yes what do you mean by internal face to stop damp? Would the Thomsons water seal not stop this? 

So would I attach the polysterene to the concrete walls or the wooden boards?

At slab level it was recomended to lay the mortar fillet, I'll shortly seal the floor then use Leyland floor paint on it too.

I thought about using sofit vents in the boarded out walls/ceiling to aid ventilation too if need be.


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## Peter Sefton (17 Aug 2013)

Hi Paul 
Welcome to the forum looks like you are getting some sound advice on the methods of insulating, when it comes to buy your insulation you could give these guys a try they sell Kingspan seconds at reduced prices.
http://www.secondsandco.co.uk/ 
Cheers Peter


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## longinthetooth (17 Aug 2013)

PAUL_TDI":2i6pfuy3 said:


> Ah just read your edited iniatial post...
> 
> Yes what do you mean by internal face to stop damp? Would the Thomsons water seal not stop this?
> 
> ...



1) 25mm gap between the most prominent internal surfaces of the conc walls and the back of the studs - then insul infilling between the studs eg 50mm studs with 50mm insul. 50mm is light for studwork so pack behind fixings (what fixings I can't quite imagine). Air gap behind studding vents at eaves through corrugations in roof cladding. 

2) Internal lining boards to studding ideally need a moisture barrier to prevent moisture in the heated room air room air being absorbrd and transmitted through to the cold side of the insulation where it might condense & rot the studding. Barrier cld be foil-backed pbd or a sheet of polythene ... This is sound practice but your shed may not be as critical an application as a fully-heated dwelling ...

Similar considerations would apply to the ceiling / roof.


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## PAUL_TDI (17 Aug 2013)

I think I follow...

Basically building a 50mm internal stud work wall, 25mm away from the concrete walls? What about if I reduced the stud work to 25mm and then used a better quality insulation like kingspan which will then foil backed for the moisture barrier.

Would I glue the insulation to the outer wood walls to stop it moving into the air gap?

All I'm trying to do here is get rid of the damp issues to a degree, I can work in the cold.

Thanks for the link Peter, very useful!


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## longinthetooth (18 Aug 2013)

Maybe better to backtrack & simplify - could you infill the receses in the ribbed conc panels w insul (polystyrene or pu foam boards)? Forget about the venting business & hope for the best. With minimal / intermittent heating its a borderline situation less demanding than a fully-heated dwelling. But I WOULD ventilate above any ceiling that you put in, & looking at the apparent ingress of daylight in the photos, the roof corrugations would seem to provide this.


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## PAUL_TDI (18 Aug 2013)

Thanks for bearing with a dumbing down  I thibk I shouldof mentioned I'm not a master at wood craft the space will be for my RC cars and normal car stuff.

I like the above plan, much cheaper and less space used.

RE....the eaves ventilation, should I let the wall boards meet the roof boards so there's some ventilation then going down the walls or leave a gap for the eaves to vent into the room? 

I can afford to loose an extra 25mm in the roof so the insulation doesn't touch the ceiling, thus allowing plenty of air movement up there.

Thanks again.


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## longinthetooth (18 Aug 2013)

If the eaves vent to the room there's no point in any insulation at all! 

The new scheme is to insulate the concrete panels in situ (cut for a tight fit if you're able to, otherwise cut undersize and foam it in round the edges). No venting on the walls. 

Ceiling needs venting ABOVE THE INSULATION, the principle is to vent the COLD side of the insulation, which is where condensation occurs, not the WARM side. 

Again, there'd no point in insulating at all if the space wasn't going to be heated.


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## PAUL_TDI (18 Aug 2013)

Thanks for clearing that up, understood.

Yes I plan to get an oil rad on a that in there.


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## PAUL_TDI (19 Aug 2013)

Any ideas on how to attach boards directly to the concrete sections? The only catch being drilling/screwing into the concrete panels voids my warranty.

I thought about undoing the bolts which hold the panels together and put some kind of strap there to bolt onto, but putting strapping then blindly trying to line up bolts on a 8x4 sheet could be awkward.

Are glues like no more nails strong enough to hold them to the wall and hold light storage on the wood.

I can fix at the top no issues by spacing out a new beam attached to the bottom roof beam.

But i'm lost at a suitable way to mount flat to the concrete. I thought about putting horizontal 1" batten along the bottom strapped to the panel bolts but didn't think it would produce a very strong mounting point?


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## PAUL_TDI (20 Aug 2013)

Well good news!

I've been told (in writing) by Nucrete that I can drill into the thick parts of the concrete panels without damaging my warranty.

So new plan.... Fill void with insulation, then attach 8x4 sheets of ply directly onto the concrete, it seems 18mm ply is a popular size to get 2nd hand from being used at site fencing. I would probably use 6 screws for each sheet of 8'x4'.

I'm looking at these wall plugs...

http://www.screwfix.com/p/fischer-sx-ny ... 100/90467#

Matched to these coach screws...

http://www.screwfix.com/p/exterior-coac ... tid=137790

Figured they would provide a good strong anchor.

I would coat/seal the back side of the ply.


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## longinthetooth (20 Aug 2013)

Those conc ribs aren't so huge in section - the fact that you're allowed to drill into them just implies that there is no steel reinforcement inside them. Fixings that are too big / too tight a fit could split the concrete rib even if just locally to the fixing. So I'd forget the 6mm coach screws and use normal woodscrews - say 5mm by 50mm or whatever seems right. Use a depth stop on the drill & go a bit deeper than the length of the screw (less the ply thickness) to leave a bit of clearance at the bottom of the hole.


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## PAUL_TDI (20 Aug 2013)

Ah yes good point, I was going a bit OTT on the coach screws..... not sure I should admit to what my first choice of fixings could be.

Indeed, thats what the company said, I can drill carefully there as there's no reinforcement.


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## PAUL_TDI (11 Jan 2014)

Well what with my first sons birth and more important things to do in the new house and having to get a bigger car the workshop hadn't really been touched at all until recently.

So for Christmas my parents kindly bought me most of the electrics I'll need for it....





several metal clad double sockets





And even 40 meters of armoured cable and a handle full of clips.

This spurred me on to splash a bit of cash on it to atleast get electrics in there so I found a local supplier of seconds insulation. I got these 4 sheets of 40mm foil backed for only £48. 





So far I have only used 2 sheets doing this...





One of my neighbours was building a conservatory and put 50mm insulation in the floor so with that I did the door...









I've found some ply seconds going cheap so hoping to get about 5 8'x4' sheets of 12mm to get 1 end done as I say to atleast get electrics in, I already have plenty of lights to go up too.

Now for a quick question, would I be able to use expanding foam and some of the 50mm insulation I have left to block the eaves at the peak of the roof? As a lot of tree debris and even worms are ending up on the floor.

So I was thinking of spraying the foam into the eaves and then stick a strip of 50mm insulation in the middle of the roof sheets stuck with the foam..





I'd like to think I'll get round to insulation the roof but can't see that happening for a while as moneys tight.


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## carlb40 (12 Jan 2014)

The eaves will need to be left open for venting. You could try attaching mesh to keep leaves/worms out etc and keep the vent.

Something similar to this
http://www.screwfix.com/p/gutter-clear- ... 10mm/88873
or 
http://www.ebay.co.uk/sch/Business-Offi ... +vent+mesh


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## PAUL_TDI (12 Jan 2014)

Thanks very much, that should do the job nicely.

Just bought some ply this morning, 12mm sheets for 8 quid each :-D might be slightly dogeared or painted one side but I'll give it all a lick of paint anyways.


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## carlb40 (12 Jan 2014)

Cool, pre undercoated ply


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## PAUL_TDI (12 Jan 2014)

Also another thought, is there any type of fixing that I can drill through the ply straight into the concrete, put a plug in then screw without having to pilot drill the ply marking the concrete, take the ply away, drill conrete insert plug then screw through board into plug?

Can see it being a very laborious task of pilot drilling each hole then removing the ply to drill the concrete.

And how many fixing points would you do per sheet? Will be using 50-60mm 5mm wood screws into those Fischer wall plugs.


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## MMUK (12 Jan 2014)

Tapcon screws  All you need is a 4mm masonary bit, just go straight through the ply.

http://www.youtube.com/watch?v=djotP-sR4mU


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## PAUL_TDI (12 Jan 2014)

My god! They look fab, will be getting them then, thanks for the link.

Think I'll go for the 57mm screws, the ribs in the walls are 75mm so should accomodate the slightly longer length than 45mm?

All the reviews are saying 5mm pilot holes?


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## MMUK (12 Jan 2014)

4mm is best. It's too easy to strip the thread out of a 5mm hole using an impact driver


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## PAUL_TDI (12 Jan 2014)

Haha gotcha. That was a worry I had after watching the video. 4mm it is then.


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## PAUL_TDI (15 Jan 2014)

MMUK THANKYOU! Those Tapcon screws are brilliant, after finding a 4mm SDS bit at BnQ I had to use 5mm in the end anyway as the concrete started to chip when trying to drive in the screws.

But they torqued up nicely with the impact driver in 5mm holes, maybe because my walls are very dense concrete?

I ended up drilling those the wall in 1 hole as I was drilling a bit deep anyway then it hit something hard and blew out. So because of this I actually drilled through the ply, marked the wall then drill the walls without the ply as I needed to see how the wall was drilling, chipping, cracking etc.

I've done the annoying fiddly end now though and pleased with the results...


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## carlb40 (1 Feb 2014)

Looks like you are getting there.


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## PAUL_TDI (2 Feb 2014)

Cheers slowly but surely!

The Mrs has started work again so on my days off I'm with my son, unfortunately it's too dusty and crampt to take him out there with me, so I sit on ebay looking for more ply and tools.

First time I got out there since those pictures today and got enough insulation installed to get a 8x4 board screwed to the wall on the left hand side of those pics. What a pain in the buttocks lifting the board above the concrete fillet so it's flat on the wall the pre drilling and drilling all the holes accurately.

Annoying bit is I need to cut a board length ways to 28" so i'm left with a 20" 8' strip I won't easily use. But once I have put the top bit of the wood on I could even think about start building my work bench so I can work out where I want sockets more easily.


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## blackrodd (2 Feb 2014)

As I can't see the work area, and am only guessing, Would cutting and fixing the boards horizontal not be more economical, and use those offcuts at above and below the windows? Regards Rodders


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## PAUL_TDI (2 Feb 2014)

I did consider but there is method to my madness.

Because only some of the ribs on the wall are suitable to drill into its better running sheets long ways so they are in contact with more suitable ribs to mount too, plus I can Mark out where to drill more easily.


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## PAUL_TDI (7 Mar 2014)

Few more pics from a couple of days in there. First were from a while back where I clipped the armoured cable to the bottom of the front gable end ply boards then took it behind the ply on the side to reach to the top right where the fuse box will be mounted.





Notice the fence panel brackets to strengthen the corners slightly.





And now more recently described a few posts back here's where I'm upto..





I also insulated the triangle above the concrete which is just timber and PVC. Here I attached a few batterns in the gaps to make an enclosed space I could then screw the ply too. First some 40mm sheet which fits nicely behind those cross beams.





Then some 20mm which brings it level.





Possibly should of measured twice on some of the ply cuts but I'm not too picky over the odd gap round the edge....




Now I'm thinking of doing the roof next, if I put the 40mm insulation sheets in then the air gap will basically be the space in the roof sheets where it undulates. Then I have 9mm OSB to board it up. I'm assuming any condensation will form on the roof panels which will then just run down to the gutters? Is there anything else to consider?

I'm nearing closer to actually getting my workbench built then I can get the spark in to power 'er up!


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## carlb40 (7 Mar 2014)

Sounds good as you will still have airflow within the ceiling.


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## PAUL_TDI (8 Mar 2014)

Awesome, will be able to get onto that next Sunday then.

Have 100 off cut sheets of 9mm OSB being delivered Monday, mainly 2.4mx0.5m so nice light strips to lift to ceiling and screw. Including the cost of "Man with a Van" will be £37. I would of collected myself but due to there early office hours I couldn't of collected easily.


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## PAUL_TDI (25 Mar 2014)

Another update...

Copious amounts of OSB now delivered as mentioned above..





My neighbour randomly knocked on the door and gave me pretty much a full 8x4 sheet of 50mm polystyrene HURRAY! I prompty used that on the ceiling...





Then back to the ecotherm for the other side..





And the front third of the ceiling is now done, could of done with someone else to help getting it square but no matter, I'll cover it up with a beam at the peak.





The OSB is a little flappy at the sides as there wasn't a third cross beam on the roof to mount too, the last 2ft is free hanging, so not sure what to do there, if anything.

There was a heavy frost the next morning and even though the workshop isn't heated yet it showed the massive difference the insulation in the roof has made.





Plan is now to paint the manky ply walls then make a start on building the workbench as I have most of the wood stored for it in the next bit of roof I need to do, problem is there's like 50 sheets of OSB on the floor now.

Any one local need some 9mm OSB lol


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## Joe Shmoe (25 Mar 2014)

Nice build diary. I'm in Essex and need OSB for my umpteen shed build. Lol.


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## PAUL_TDI (25 Mar 2014)

Cheers, bit slower than others on here.

Well once I've sorted out what would I need I'd sell you the rest. I'm in Braintree by the way, seeing as essex is fairly big.

At the moment I've only used 8 offcuts and will only been about another 15-20 for the roof. Instead of hard cash I would swap for 12/18mm ply, timber or insulation board.


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## PAUL_TDI (4 Apr 2014)

Currently thinking about painting where I'm up too so I can then build my workbench in situ and move in my other bench from my shed. Then I could actually get the sparky in (when funds allow), I'm waiting until the bench is built so I know where I want the sockets, possible a bit backwards way of doing it but I'm very much prefer to "see" where things need to go rather than drawings.

I want to keep costs down when painting but also don't want damp to wreck the paint in a year etc. So my thoughts were to give the ply a PVA wash and find a cheapish paint in a lightish shade of grey. But is emulsion, matt, silk best!?

Something like this....

http://www.wickes.co.uk/trade-silk-pain ... vt/214421/


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## carlb40 (5 Apr 2014)

I would skip the pva and just paint it, plus i would use white to keep it as bright as possible


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## PAUL_TDI (5 Apr 2014)

Good news then, one less thing to do haha.

I'll stick with the light grey so it doesn't get as dirty as quickly, plus grey will still be a hell of a lot brighter than the dirty ply colour it is now.


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## MMUK (5 Apr 2014)

PAUL_TDI":pd5v14q9 said:


> Good news then, one less thing to do haha.
> 
> I'll stick with the light grey so it doesn't get as dirty as quickly, plus grey will still be a hell of a lot brighter than the dirty ply colour it is now.




It'll look like the inside of HMS Invincible :lol: :wink:


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## PAUL_TDI (6 Jul 2014)

Well it's only taken 11 months to get electric down there but now it's in I'm just itching to get my bench built and actually start using it for other things other than building it.

As always, pics speak a thousand words...

Mu twin security light, 1 pointing towards the path to the house, then one for more towards the shed and workshop doors aswell as Penny the ferret should we need to attend to her later in the evening.





Here is my impatient mount of the light so my spark didn't have to try and get a good fit directly to the concrete. Impatient being that in future I'll wait A LOT longer between coats.





Thankfully due to the forward thinking (read: fluke) My ply lining had a small 2'x1' board on the other side of where the security light was going, so I was able to remove this board and insulation and drill some holes, 1 for a screw to mount the mount and 1 slightly larger hole which matched up with a hole in the mount to pass the cable inside neatly.





I only have power down this end because everywhere else is basically going to be storage. My Dad donated me the rather handy sliding spot lamps.





And my father in law donated me this double flourescent tube unit which lights the rest of the workshop very well. My sparky made a couple of timber mounts to get it to sit where I wanted it.





Then away from the electrics after a few failed attempts I finally got my grubby hands on some steel racking each shelf being 3'x2', I have only used 5 upright lengths to do this so far;





I still have 5 left and more shelves than I can shake a stick at! Possible bargain for the build, 35 quid for 10 uprights, 21 shelfs, bag of bolts and some cross braces from another type of racking. I have to say after looking more closely at the uprights it's Dexion 225 slotted angle stuff......£110 odd for 5 uprights!!!!! Couldn't believe my luck after being picked to the post on ebay and facebook twice already.

I've got my eye on some 8x3 reclaimed beams to use as my bench top, I already have some old 4x4 fence posts for the legs, some 4x2 for the main top frame and plenty of 3x2 and 2x2 for various other cross member and bracing.


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## PAUL_TDI (25 Jul 2014)

I've still not had a chance to start work on my bench.

However my old workbench is now in the right building at least..









And the shed got the OSB treatment mainly to try and use some of the offcuts that are still in the workshop.





I have a few woodworking tools on there way to enable me to build the bench in the coming weeks.


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## PAUL_TDI (7 Aug 2014)

So when you go to start building your workbench out of lovely reclaimed timber only to realize that its very twisted, now I'm sure a good carpenter could of made do with it and made adjustment to the joints, but I didn't want that problem to overcome.

So bought the cheapest wood I could find which happened to be fencing timber.





4 hours of labouring over the above has left me this....









I've also got the front upper and lower beams cut with joints, so will do the back ones then assemble front and rear frames.

I also made my first little project in the workshop last weekend...









Base and stalk are made of spare timber I have knocking about and the 'house' is made out of pallet slats. I've since given it a couple of coats of yacht varnish.


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## PAUL_TDI (16 Aug 2014)

The finished (nearly) article.

Top side rails on, annoyingly my 4x2" timber was smaller than the fencing 4x2, so the sides sit a little lower.





Bottom side rails in, no fancy joints here.





Prepared bracing for the bottom shelf









Put some side cross braces in





Very pleased with my cutting for the nifty fit





And in situ...









Will probably get 4 lengths of 6x3" for the top and use some thin ply as a back board.

I'm very pleased with it, even without the top on it doesn't wiggle a mm, only rocks a couple of mm where I have placed it due to bad floating on the concrete as it's where my electrics pipe poked through the floor.


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## PAUL_TDI (29 Aug 2014)

Another trip to Wickes today, I bought 6.0x100mm screws for the top, by the time I drive them through the top 10-15mm that will leave a good 25-30mm in the frame.

I have also bought my first plane! An old Record No.4, it needs cleaning up a little but it was in usable condition which was the idea for the time being to shave down the heights of my shims on the ends, which after a little sharpen up on the wet stone it worked very well, even with my limited knowledge on plane adjustment and use.





Dodgy crack in handle (tote?)





In the end I bought 9x3" for the top as it's all my local yard had in 3" thickness which they insisted on me buying the offcuts. I've trimmed the 9x3" off cuts to fill some of the space at the back which will leave me with a 24x4" tool well at the back, which I'm trying to build with slopped ends for easy brush out.

The pics...

Trimmed and glued a thin plank to the top of the side rails...





I used the circular saw to cut the excess off which turned out to be tall enough to glue straight onto the other end. I then used the plane to bring down the shims to the correct height so they were flush with front and back.









A little mock up of how the top will be...


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## PAUL_TDI (29 Aug 2014)

Got some more time out there this afternoon.....

First plank glued and drilled readying to be screwed down...





I don't have any long clamps so out came the ratchet straps to pull the planks into position before screwing





So the back part is made up on some 3x2 with a 45 degree cut as each end, some 12mm chipboard in the middle, merely to raise the bottom and then 9mm ply on top.









Voila....









Just need to the trim the ends, once thats done I'll mount the back board properly, Just has a couple of screws in at the moment for the pics.


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