My new workshop

[colinc]

Hi,

after having learned so much from the various WIP postings here, I thought that I should share my experience here as I build my own new workshop.

I am going to keep the individual posts quite short as I just wrote a long one and then lost it as the system had logged me out! #-o I hope that's ok?

regards,

Colin

 

[colinc]

Background:

Last year, whilst the kids were away, we down-sized to a bungalow (although I think that having finished at University, they have now found our address and have plans to come home). Whilst the new home didn't have a garage as it had been converted to living accomodation, it was otherwise ideal and as part of the deal, management allocated a corner of the garden for a my new workshop.

Planning:

I suspect that like me, many people are a bit daunted by the planning process, and I put a lot of effort into trying to design something with a flat roof that would stay below the 2.5m limit applicable to my allocated site. In the end I realised that it was just too much of a compromise as I really needed a taller building with a pitched roof, and I decided to go for planning. In reality, the process was very simple and the local planning officer was very helpful. I submitted some simple cad drawings and the application form via the planning portal, paid my fee (I think £170), and six weeks later got a letter giving me the go-ahead.

I really would urge anyone who has the same dilemma as I did to not compromise on height, and talk to the local planners. I got the impression that as long as I wasn't going to anything outrageous and the neighbours didn't mind, they really weren't too bothered what I did in my own garden.

regards,

Colin

 

[colinc]

Last weekend I started the clearance of the land. It was part slabbed (onto soil) with a greenhouse and various shrubs which I have removed.

I have started removing topsoil into a skip at the front of the house but quickly remembered that the volume of soil is much greater when dug out than it is when in the ground. A message on the village's email list (we are organised here) found a couple of takers for as much topsoil and slabs as I could dig out, so whilst it's not as quick as just calling the skip company to take it away, it means that nothing goes to land-fill and I get bottles of red wine in exchange to enjoy whilst I rest my aching bones.

I found that I had six fruit tree/conifer stumps to remove. To get them out I have had to resort to digging around and beneath them with a trowel cutting out roots as I go - currently three down and three to go.

Hopefully, if the weather holds out and I can get rid of the current load of soil in the skip I can get the ground ready for hardcore over the weekend. A friend has offered to loan me a whacker plate to compact the surface. My current dilemma is how deep to go? I am very aware that much that I dig out needs replacing with hardcore that I have to barrow in.

As far as concreting goes, I have had a quote from a local pumping contractor and it should hopefully only cost about £200 + vat to pump 5 cu. m. of concrete in for the slab.

 

[Phil Pascoe]

Colin, if you write a long post it pays to "save draft" - it can prevent losing it. Just retrieve it and add to it if needs be.

 

[colinc]

Colin, if you write a long post it pays to "save draft" - it can prevent losing it. Just retrieve it and add to it if needs be.

Ok, thanks, I'll try that.

Something that is a bit unusual about my shed is that it is a bit of a prototype for a kit approach I am interested in. I have a particular problem in that because of its proximity to the boundary I need either to get building regs approval or build it of 'substantially non-combustible material' in order to get an exemption from building regs. (it will be <30 sq. m floor area). That rules out a timber frame.

Instead, I am planning to construct a light gauge steel portal frame as the structural part of the building and use light gauge steel 'stud and track' panels for the walls. Here is a picture of the engineering model of it that I made a while ago:



Obviously this is not something that everyone can do, but because I work in this industry, I can do this easily. The benefit of this approach is that I can order a kit of parts from the factory that comes pre-punched and ready to bolt/screw together. The idea is that I erect the portal frame and purlins, then lay two courses of bricks around the slab perimeter, then bolt the wall panels together and lift them into position on top of the walls (they bolt to the columns and eaves beams. I have checked the costs and this approach is not really any more expensive than doing it in timber and is potentially a lot quicker to put together if I get the details right. It is also much easier to meet the non-combustitible materials requirement using steel.

regards,

Colin

 

[Harbo]

Looks interesting but what are you doing about insulation?


Rod

 

[colinc]

Looks interesting but what are you doing about insulation?


Rod

At the moment, I am undecided about the roof. My planning application was based upon using insulated composite profiled steel cladding panels, but I am leaning towards using timber rafters over the purlins and using Cembrit artificial slates (apparently even with all the timber this counts as non-combustible) with plasterboard under the rafters, in which case I will use Celotex between the rafters. The roof design allows for the weight of tiles so I have many options and I am open to changing my ideas as the project evolves.

The walls will be a mix of materials. As the rear and side elevations are barely visible to anyone, I have approval for profiled metal sheeting with insulation within the stud and track panels and a plasterboard lining. However that could be changed to composite panels if I can get a good price.

To the two front elevations my plan is to use Marley Cedral cladding which is an embossed fibre cement weatherbord profile panel: http://www.marleyeternit.co.uk/Facades/ ... Click.aspx although if budget allows I would like to use this on all the elevations. The insulation will be rockwool in the stud wall cavity.

I have also allowed for a floating floor over the slab with 50mm Celotex in it.

Have I got enough insulation? One of the reasons I didn't want to use masonry construction was to keep it all lightweight and fairly easy to heat up.

Colin

 

[MickCheese]

On my workshop I have felt shingles. Never tried them before but were very easy to lay, are lightweight and waterproof.

After all a lot of American home have these not tiles so they must be reasonably ok.

Mick

 

[Phil Pascoe]

Mick - any idea of cost per metre, please?

 

[colinc]

On my workshop I have felt shingles. Never tried them before but were very easy to lay, are lightweight and waterproof.

After all a lot of American home have these not tiles so they must be reasonably ok.

Mick

Unfortunately felt shingles are out too because they don't have the right fire rating class. They cost about £15 per sq. m. at Wickes rates. I would have seriously considered them had I not had the limitations on materials imposed by the building regs exemption requirements (not really an exemption I guess, as they still regulate what you can use).

To achieve the requirements my roof choice is really down to tiles, fibre cement sheets or plastisol coated profiled steel sheets. I am only really considering using either tiles or profiled steel. My planning permission is for steel and there is a place locally who sell Kingspan's odds and sods at reasonable prices: http://stores.ebay.co.uk/Actionclad...10481505&_sid=374311016&_trksid=p4634.c0.m322

Colin

 

[colinc]

Hi,

just a quick update in case anyone's interested.

I have now erected the structural frame which took a day and a bit to put up. Not a bolt hole detailed in the wrong place and everything a perfect fit, so I am quite pleased with myself:



I have now put in the two courses of brickwork around the perimeter and started on the stud and track wall panels (only the back two in the picture so far). They sit on top of the bricks but are bolted to the frame. The wall panels screw together with self-drilling screws so are a bit more fiddly to set out than the structural frame, but everything is pre-cut to length so it is very easy to work with:



The nearest corner column in the picture is going to be cut off below the eaves beam level, and the door goes diagonally across the corner to give me a good and wide access from the garden for large parts like wings (the gate and some of the planting in the picture will be gone). Once I have the metalwork completed and all the side bracing in, I can start to think about roof joists and tiling. I also need to order the Cedral for the sides but that requires a decision about the colour which I am putting off but will probably delegate to the female members of the household.

I am planning to lay a dpc over the slab, then insulation and a chipboard floor over that. Has anyone done similar? I am wondering if I should put battens down or just let it float on the insulation?

regards,

Colin

 

[colinc]

Looks interesting but what are you doing about insulation?Rod

The walls will be filled with rockwool (the sound deadening variety) between the studs. The roof will have joists over the steel purlins and plasterboard under. Am planning using 200mm glass fibre within the depth of the steelwork beneath the rafters, with a ventilated void above. The floor will be 50mm of Celotex. Windows all double glazed to current standards.

The idea is to get a reasonable level of insulation so that I can keep it warm economically overnight when gluing. I use mainly something called Aerodux which is a 2-part resorcinol-formaldahyde resin that needs to be be kept reasonably warm whilst it is curing.

regards,

Colin

 

[monkeybiter]

I am wondering if I should put battens down or just let it float on the insulation?

When I had my extension built I agreed to a floating floor on insulation.

That was a mistake [due to misplaced trust and a lack of research] as the insulation has compressed [slightly] in places of high traffic and the floor now flexes underfoot in places.

Had I thought about it at the time, and now that I have, I would strongly recommend flooring grade board on battens with insulation between.

 

[longinthetooth]

Doesn't all that steelwork provide galloping thermal bridging?

 

[colinc]

Mike, that's what worried me. What material did they use for insulation?

Colin

 

[devonwoody]

Like your post and project.

 

[colinc]

Doesn't all that steelwork provide galloping thermal bridging?

Hi,

no, there is no continuity between the outside, the steel and the inner finishes, there are battens and building boards in the construction that provide thermal breaks. There is of course scope for condensation on the steel in the cold cavities if warm air gets in, but appropriate vapour barriers and ventilation in the right places will take care of that. It's now quite a commonly used method of construction for low-rise commercial buildings and increasingly so now that the fire services have had bad experiences with timber frame in a few old-folks homes etc., and I have even seen it used in housing recently.

Steel framing's all a bit OTT for a garden shed, but in my situation it's an easy and cheap option. I would have liked to use timber frame construction but it wasn't possible due to the requirement for non-combustibilty.

Colin

 

[monkeybiter]

Mike, that's what worried me. What material did they use for insulation?

Colin

Celotex ~125mm, can't see the type.

 

[JanneKi]

Doesn't all that steelwork provide galloping thermal bridging?

the steel in the cold cavities if warm air gets in, but appropriate vapour barriers and ventilation in the right places will take care of that. It's now quite a commonly used method of construction for low-rise commercial buildings and increasingly so now that the fire services have had bad experiences with timber frame in a few old-folks homes etc., and I have even seen it used in housing recently.

What do you mean? In general here in Finland wooden frames are considered safer by fire department - IF fire catches. Of course steel does not catch fire, but it has the problem of loosing it's strenght very rapidly in heat and the steel frames collapse in an unexpected manner. It's not typically the structures that burn - even stone houses burn, but that's due to the interiors (furniture, floorings, interior walls, paints etc.). The wooden frames have a very predictable behavior and at least here, they are therefore considered safer for firemen than steel frames.

For high risk areas the steel frames (like high houses) have to be fire proofed by one way or another - insulation or overlaying with concrete or some other means.

 

[colinc]

Doesn't all that steelwork provide galloping thermal bridging?

the steel in the cold cavities if warm air gets in, but appropriate vapour barriers and ventilation in the right places will take care of that. It's now quite a commonly used method of construction for low-rise commercial buildings and increasingly so now that the fire services have had bad experiences with timber frame in a few old-folks homes etc., and I have even seen it used in housing recently.

What do you mean? In general here in Finland wooden frames are considered safer by fire department - IF fire catches. Of course steel does not catch fire, but it has the problem of loosing it's strenght very rapidly in heat and the steel frames collapse in an unexpected manner. It's not typically the structures that burn - even stone houses burn, but that's due to the interiors (furniture, floorings, interior walls, paints etc.). The wooden frames have a very predictable behavior and at least here, they are therefore considered safer for firemen than steel frames.

For high risk areas the steel frames (like high houses) have to be fire proofed by one way or another - insulation or overlaying with concrete or some other means.

Hi,

Co-incidentally, I work for a Finnish construction technology company, but am based in the UK.

You have picked up on a short comment about a big subject. For small structures I don't think that there's any issue, each way has its advantages and in your part of the world the advantages of timber frame construction far outweighs the disadvantages. It's in the middle sized buildings over here where there are issues. After a couple of high-profile incidents there is a lot of concern about problems in medium to large timber frame structures and the fire services are pressing for changes in building regulations due to concerns about rapid spread of fire, most particularly during construction where timber frame is at its most vulnerable. This is a good summary and links to more specific issues: http://www.cfoa.org.uk/11064 In Finland there is a long tradition of timber construction and perhaps therefore more experience but it has seen changes too. Probably your building regulations are currently better developed than ours in that area. Am I right in thinking that prior to building reg changes (in 1997) in Finland timber was only allowed for low-rise but since then something like four storeys are allowed?

I understand that there he problems have arisen where small fires have rapidly escalated and spread faster than the fire services anticipated causing risk to personnel and adjacent property. A big driver behind construction methodologies in the UK is insurance. Insurers like masonry construction which is why we still build houses mainly with brick and block. Incidents like these have encouraged construction companies to look for alternatives to timber and so steel framed panels and cement based boards are seen as an alternative.

Of course, non of this is relevant to my little shed given its size and position. I am simply using steel framing because it satisfies the regulations that govern my choices (and I can now lift engines from the roof trusses).

regards,

Colin