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Loft conversion v "boarding for storage"


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I am building my layout in the loft. I don't regard the situation as excessively unsafe but we have had a reinforced floor installed across the main beams (which are huge) and we have non-combustible ceiling insulation. We have a rotary ceiling vent in place to remove hot air and improve circulation and the single method of access is via a wide loft ladder.

 

I don't know whether this would be considered a habitable area here but I have no concerns with the arrangement at all.

 

The primary benefit is space and this is the key issue considering there are no alternatives that could provide an equivalent area. The main drawbacks are access (which is OK but not ideal ), the summer loft termparatures here in WA and the issue of ingress of dirt. To overcome the latter I have lined the loft from layout level upwards.

 

Rgds

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  • RMweb Gold

It might be a bit simplistic and stating the obvious, but Lofts are as they are for a reason......They are just a space between the roof and the ceiling of the rooms below.

 

It rather worries me that anyone advocates others to use the space as a hobby room to be honest; even with a proper loft conversion* (bout £5000) you still end up with a room that in most houses is barely fit for purpose and can add cosiderably to the rateable value.

 

The same money spent on a Garden Room as they now call posh sheds is sooo much better an investment

 

 

*I don't mean the full works with dormer windows and en suite bathrooms etc ;)

 

Agreed you might get pinged for more Council Tax (about £100 per year). But, so long as providing proper access (i.e. via stairs) can be done without compromising other rooms in the house, a loft conversion is a sound investment in most houses. Sure, it is a very expensive way to have space for a model railway, but as an extra bedroom it will usually add far more value to your home than it will cost. Whenever possible, put the pipework in for an extra bathroom but don't go to the cost of installing the bathroom which will only get in the way of the railway. Even the best garden room/workshop will not add much to the value of your home, especially if it takes up too much of the garden.

 

The other good option is a bigger garage. Not expensive to build but much in demand.

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  • RMweb Gold

Extra joists (at least 150mm but quite possibly more depending on span), yes. At 90 degrees, NO. All that would do is impose extra load on the original joists.

 

When working out spans, be very careful to only consider load bearing walls. In many houses, only the external walls at 1st floor level are load-bearing.

 

I am trying to remember our carpenter's rule-of-thumb for calculating joists. But, as an example, our 5m wide sitting room needed (IIRC) 200mm joists. Consult a structural engineer if in ny doubt.

 

In most cases, it will be very difficult to get suitable joists up into the loft without taking down a ceiling.

 

And, as others have said, don't play fast-and-loose with fire regs. They are there for a reason. Don't put your life at risk and those of others. If using a loft, you really do need a window from which you can escape.

There is - as you probably know (others might not) a standard table giving the timber sizes for load bearing over various distances. My attic has very deep joists as it was designed to full load bearing spec for the floor and the pre-assembled trusses were sized accordingly (I only changed the use in retrospect and after the job had been spec'd - the only change being not to include the stairs and firedoors). The pic below shows the depth of the joists that was needed to meet the spec for a load bearing floor (although the span also played a part of course).

 

post-6859-0-84581700-1344421549_thumb.jpg

 

As Mickey has just said - the space between the uppermost ceiling and the roof is there for a reason - basically to hold up the roof, not to provide a full load bearing floor and certainly not to provide habitable space unless constructed accordingly (my roof trusses came with paperwork specifying what floor loading they can take, but then I was building new). There are a number of folk in the building trade contributing to this thread (I'm not one - I'm merely an amateur bricklayer) and I have linked already on Page 1 to some relevant official information - I reckon sources such as them are the ones to listen to. And incidentally I found a link on the 'net to someone asking questions about buying a house that had received a large attic conversion but clearly not in accordance with Building Regs and their surveyor wouldn't sign it off, another party was clearly in the position of not being able to sell it in that state as there was no paperwork to go with the attic conversion.

 

A proper attic conversion job isn't cheap - end of story.

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  • RMweb Gold

Nice photo that. Illustrates the situation very well.

 

How wide is the bit that you can actually have a layout at reasonable height from the floor?

 

Scares me some of the photos we see on layout threads. Layouts have clearly been built in roofspaces that are constructed with lightweight trusses (50 x 25) and, in some cases, even suspended from them.

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Not sure I follow the Rates/Council Tax argument. AFAIK all the houses in our street are the same CT band irrespective of extensions/conservatories/garages etc. I do remember thw dim and distant past when doing anything (including putting central heating in) would up the rateable value.

 

Ed

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  • RMweb Gold

Nice photo that. Illustrates the situation very well.

 

How wide is the bit that you can actually have a layout at reasonable height from the floor?

Basically - if it went right up to where the ceiling start to slope in (i.e. where the vertical timberwork can be seen) it would give a space at least 12 feet wide by 20+ft long but the 'reasonable headroom' area is much smaller. Regrettably due to planning objections I had to drop the roof ridge line quite a bit and that in turn bashed down the usable height in the attic - hence my stepping back from the staircase and fire doors and turning it into solely storage space, albeit interior wise fully up to habitable space standards (I overlooked knocking plastering out of the spec and it need to be wired anyway for lights and power point). And I'm glad I did as it is now very full storage space and when I'm up there I'm forever banging my head!

 

Fortunately we did sufficiently well out of the sale of our previous house to have enough money available to build a new garage - which strange to relate has an insulated partition wall slightly off-centre between the bit with the big door and the bit with a plain (fully insulated on the inside) brick wall.

 

post-6859-0-72848300-1344423188_thumb.jpg

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Basically - if it went right up to where the ceiling start to slope in (i.e. where the vertical timberwork can be seen) it would give a space at least 12 feet wide by 20+ft long but the 'reasonable headroom' area is much smaller. Regrettably due to planning objections I had to drop the roof ridge line quite a bit and that in turn bashed down the usable height in the attic - hence my stepping back from the staircase and fire doors and turning it into solely storage space, albeit interior wise fully up to habitable space standards (I overlooked knocking plastering out of the spec and it need to be wired anyway for lights and power point). And I'm glad I did as it is now very full storage space and when I'm up there I'm forever banging my head!

 

Fortunately we did sufficiently well out of the sale of our previous house to have enough money available to build a new garage - which strange to relate has an insulated partition wall slightly off-centre between the bit with the big door and the bit with a plain (fully insulated on the inside) brick wall.

 

post-6859-0-72848300-1344423188_thumb.jpg

 

In view of another topic on here lately you could do well renting that to some illegal immigrants! :O

 

Ed

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  • RMweb Gold

There is - as you probably know (others might not) a standard table giving the timber sizes for load bearing over various distances. My attic has very deep joists as it was designed to full load bearing spec for the floor and the pre-assembled trusses were sized accordingly (I only changed the use in retrospect and after the job had been spec'd - the only change being not to include the stairs and firedoors). The pic below shows the depth of the joists that was needed to meet the spec for a load bearing floor (although the span also played a part of course).

 

post-6859-0-84581700-1344421549_thumb.jpg

 

As Mickey has just said - the space between the uppermost ceiling and the roof is there for a reason - basically to hold up the roof, not to provide a full load bearing floor and certainly not to provide habitable space unless constructed accordingly (my roof trusses came with paperwork specifying what floor loading they can take, but then I was building new). There are a number of folk in the building trade contributing to this thread (I'm not one - I'm merely an amateur bricklayer) and I have linked already on Page 1 to some relevant official information - I reckon sources such as them are the ones to listen to. And incidentally I found a link on the 'net to someone asking questions about buying a house that had received a large attic conversion but clearly not in accordance with Building Regs and their surveyor wouldn't sign it off, another party was clearly in the position of not being able to sell it in that state as there was no paperwork to go with the attic conversion.

 

A proper attic conversion job isn't cheap - end of story.

 

Stationmaster, you have attic trusses which as you know are calculated as a whole unit so in effect the floor as well as spanning also hangs (if that makes sense), the strength is as a whole unit, for example the floor and roof above my railway room is also attic trusses, they span 8.5M the joist depth is approx 200mm, if I were to have spanned that with TJI joists they would of been 275mm (IIRC) in timber I don't think we could get anything to span that without introducing a steel.

 

looks good, so much easier from scratch.

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  • RMweb Gold

200mm is 8 inch, so they are proper joists :)

 

Why do people use French measurements on here?

 

8 inch is 8 inch there shoudlnt be any need to convert from Foreign idiot measures to good old imperial that works

 

 

and before anyone says ....Builders yards still know the proper way to measure....I wont count in owt else

 

I do usually use inches when talking timber. Perhaps the staff at your builders' merchants are older than the guys at my local Travis Perkins. They look completely confused if I don't talk in metric.

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I have read this thread with interest and must say that I am very firmly in the do not use the loft for a layout room camp unless it is a proper conversion into a habitable room. I looked at using my boarded out loft as a layout room but decided not to due to the dust, extremes of temperature and general unpleasantness. Converting mine into a habitable room was not an option as providing Part B compliant MOE to the ground floor exit would have lost more usable floor area on the lower floors than I gained from the conversion (and therefore was a bit pointless).

 

I am probably now going to reiterate what a lot of people have said already, for that I apologise however it is probably worth saying again (I'm also probably going to get lynched by the people from the "its my house I can do what I want" camp, which is fair enough as everyone is welcome to their opinions).

 

There has been a lot of talk of doing "half" loft conversions and installing velux windows, strengthening floors etc but not installing stairs. This is fine, however you should still get Building Regulations approval (either through an Approved Inspector or the Council). Through the council takes longer but is cheaper than an approved inspector. If you do not do this and come to sell your house the buyers lender will almost certainly not approve a mortgage on the property without either Building Control approval for the alterations, the alterations removed or a building regulations indemnity policy (which is another can of worms all together). If you are buying a property DO NOT believe any Estate Agent who says that your lender will lend on a property with an unnaproved loft conversion (or similar) if it is not advertised as a habitable room, this is simply not the case and any Mortgage Surveyor has a duty of care to his / her clients to report any recent work that has not been approved. Lenders have tightened up on this significantly in the last four years or so and are much more particular on what they will or will not lend on. Additionally unapproved structural work will invalidate your buildings insurance.

 

If you are thinking about boarding out your loft there are still a lot of things to consider. The difference between the load bearing capacity of a ceiling joist and suitably sized floor joist has already been discussed so I won't go into that, as has the general purpose of roof space in a property. If you are thinking of laying boards and there is insulation between the ceiling joists you must provide a suitable gap for ventilation between the insulation and your boards otherwise condensation will develop on the underside of your boards creating mould and potentially rot. You also need to consider condensation in your roof space from either you being up there or general activites in your house below, this can be dealt with my things such as adequate ventilation, sealed loft hatches and semi permeable membranes, you will need to decide what will work in your property as one solution will certainly not fit all. It should be fairly obvious the potential for damage to the roof structure caused by condensation.

 

Whatever you are doing in your loft you will obviously need power and lighting. Do not install this yourself unless you are a qualified electrician. Basic power and electrics may seem simple, however to prove my point in my professional life I have recently been involved in an horrific incident where the permanent live had been wired to the earth on a light fitting by mistake, meaning that the fitting itself was live.

 

In summary, a properly approved and constructed loft conversion will add value to your house and provide a good railway room. However for some houses this would not be feasible, if it isn't, I wouldn't even contemplate boarding out the loft and would look at other areas to house the layout.

 

Regards,

 

Jon

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  • RMweb Gold

The builders I used on our current house worked in metric all the time as for joist sizes you can ask for 4x2 or 8x2 I doubt that you will get the exact size unless you specify that they must be exact. 4x2s are often 100-95x45mm a bit of a problem if they are less than 100 and the insulation is exactly 100.

 

post-8525-0-56206200-1344497169_thumb.jpg

 

 

The picture shows a previous loft conversion. It required removing the braces to the purlins hence additional load was placed on the side walls which was supported mid span by the floor. Hence it required 8x3 joists to support the foor and the roof load. Cost £300 for a set of calculations from a structural engineer. I just drew up what I planned to do he did the calcs and confirmed timber sizes. It avoided a site visit which would have increased the cost.

Insulation was multi layer foil stapled to the rafters 2x1 cross battems then plasterboard. I did get a professional in to do the plastering as I didn't think I could cope with a 24ft obtuse angle between the sloping bits and the ceiling. New stairs etc. All that work then a familly issue forced a move however I got my money back plus some at a time when the market had dropped.

Don

 

Ps the end window was needed to meet fire regs as the veluxes were too high for acess in case of a fire.

post-8525-0-56206200-1344497169_thumb.jpg

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  • RMweb Gold

Mickey said

200mm is 8 inch, so they are proper joists

Why do people use French measurements on here?

 

8 inch is 8 inch there shoudlnt be any need to convert from Foreign idiot measures to good old imperial that works

and before anyone says ....Builders yards still know the proper way to measure....I wont count in owt else

 

Attic trusses are not joists, a joist would be 200 x 47 or in the 19thC 8"x2", trusses are usually (but not always) between 38-45mm ( 1 1/2" -1 3/4")

 

The max span of a 200 x47 would be 4.07M (or 4070mm or 13' 4" 3/16ths. . . . .so much easier with Metric) and that is at 400mm centres.

To span say 5M would take 220x75mm again at 400mm centres.

 

You have some odd merchants near you if they still work in imperial, they may sell timber as 4x2 or 8x1 etc but it is metric, the lengths timber is imported in for instance are, 2.4m, 2.7m, 3m, 3.3m, 3.6m, 3.9m, 4.2m, 4.5m, 4.8m, 5.1m,5.4m, 5.7m etc.

They are the Metric for the old 8', 9', 10', etc.

None of the merchants work in imperial, some customers may ask for old sizes but that is not what they are being sold.

 

I don't like the French but Metric is far better for the building industry.

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. If you are thinking of laying boards and there is insulation between the ceiling joists you must provide a suitable gap for ventilation between the insulation and your boards otherwise condensation will develop on the underside of your boards creating mould and potentially rot. You also need to consider condensation in your roof space from either you being up there or general activites in your house below, this can be dealt with my things such as adequate ventilation, sealed loft hatches and semi permeable membranes, you will need to decide what will work in your property as one solution will certainly not fit all. It should be fairly obvious the potential for damage to the roof structure caused by condensation.

 

 

Good point re condensation and worth bearing in mind should you take up the offer of cheap additional top up loft insulation through grants etc, as I have seen a number done by so called experts where the insulation has been shoved right up to the eaves, blocking airflow into the loft and creating horrendous condensation. Also a common problem is the power cables for electric showers being buried under insulation, which is a serious fire risk.

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  • RMweb Gold

Except when you are trying to match into old brickwork (not that I need worry about that in the garden nowadays)

 

Just this week ordered 3 packs of Imperial swanage soft reds.

 

Cost more but can be done.

 

TBH we usually use wallstarters.

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  • RMweb Gold

Looking at estate agents' windows last night. Who needs a loft conversion? rightmove.co.uk/property-for-sale-35003983.html. I think the architect must be a model railway enthusiast.

Now how do I persuade SWMBO to move to the other side of town???

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  • 4 weeks later...

It's a bit late in the day but I'd been meaning to provide a picture of one of the main joists in our loft space that I referred to in my earlier 8 Aug post.

 

In true Aussie style let me say "that's not a joist, this is a joist" :

 

post-1342-0-60165600-1347204902.jpg

 

I positioned the UK mains plug as a size reference

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