What's involved in a DIY Loft Conversion - any useful guides

[405 TD Estate]

Hi,

I have a nice large loft in my end-of terrace house which would make a
lovely bedroom with an on-suite bathrom. I don't want to build out of
the roofline just put some windows in. The stairs I would like to run
off the landing (a proper staircase) which runs parallel to but above
the original staircase.

So what's involved for the DIY'er?

Also it is worth doing it to building regs etc or just do it to my
satisfaction (I would want to make sure there is a decent means of
escape and no problems with damp etc)


My thoughts so far are :

I need approval to convert the loft though there is a possibility it
is exempt?

I need to find all building regs relating to this - I would appreciate
if people could give me pointers

The difficult bit will probably be the floor - Obviously It will need
strengthening but do you have to take the roof off to get large beams
in? How do you do the calculations?

Any useful guides 'how to's' would be good.

 

[Ron Lowe]

Hi,

I have a nice large loft in my end-of terrace house which would make a
lovely bedroom with an on-suite bathrom. I don't want to build out of
the roofline just put some windows in. The stairs I would like to run
off the landing (a proper staircase) which runs parallel to but above
the original staircase.

So what's involved for the DIY'er?

Also it is worth doing it to building regs etc or just do it to my
satisfaction (I would want to make sure there is a decent means of
escape and no problems with damp etc)


My thoughts so far are :

I need approval to convert the loft though there is a possibility it
is exempt?

I need to find all building regs relating to this - I would appreciate
if people could give me pointers

The difficult bit will probably be the floor - Obviously It will need
strengthening but do you have to take the roof off to get large beams
in? How do you do the calculations?

Any useful guides 'how to's' would be good.

The structural issues are the paramount ones in the first instance.
I'd STRONGLY reccomend you get a structural engineer involved at the design
stage.
TBH, I'd get an architect to do the planning and to subcontract a structural
engineer.

There are several structural issues.

Firstly, if your roof is made from lollipop sticks ( like many are ), then
there will be a bunch of internal bracing timbers in the loft, which will
need to be removed. The load taken by these will need to be transferred to
alternative structures. This may involve steelwork A-frames, or timber
re-inforcements, limiting the width of the new room to accomodate some
bracing behind the lie-ins, or total roof removal and replacement.

Then there's the floor to worry about.
The existing timbers will not be adequate for floor loading, most likely.
The solutions vary from stiffening the existing timbers, steelwork,
additional verical support installed inside walls in the floor below etc
etc.

Then there's insualation specification

Then there's all the building regs around bathrooms: Ventilation, drainage,
etc, etc.

The design of a loft conversion ig in general not a DIY issue, although much
of the actual work could be.

Building controll will *certainly* need to be involved in this.

Please understand that you are undertaking a serious structural alteration
to the building, and this has serious safety implications if done badly.

There is no website that we can point you at that explains it all easily for
the DIYer. It's beyond that. ( the design parts, I mean, not the actual
work. )

 

[405 TD Estate]

I found this :

http://www.bathnes.gov.uk/BathNES/environmentandplanning/buildingcontrol/loftconversions/default.htm

Basically Bath Council's Building regs or interpretation of them -
very useful

Any more practical pointers are welcome though....

 

[Ken H]

http://www.bathnes.gov.uk/BathNES/environmentandplanning/buildingcontrol/loftconversions/default.htm

Basically Bath Council's Building regs or interpretation of them -
very useful

How does the law define a "habitable room" (in the loft)? I boarded my
loft out back in 1993. I was careful to make the loft ladder/stair
removeable (due to some clause in the regs which I forget). The two
Wickes' skylight windows I put in the roof in the roof are way above
the height-above-floor level of the current regs. Will this run me
into problems when I sell the house?

Ken H

 

[John Rumm]

So what's involved for the DIY'er?

Well in blue peter tradition, here is one I did earlier:

http://www.internode.co.uk/loft

Also it is worth doing it to building regs etc or just do it to my
satisfaction (I would want to make sure there is a decent means of
escape and no problems with damp etc)

Doing it with full building regs approval is an absolute *must*.
Otherwise you will run into all sort of potential problems later.

Looking at it another way, there is nothing that onerous about doing it
by the book (the regs regarding loft conversions are actually quite
sensible and well worth doing), so you may as well.

My thoughts so far are :

I need approval to convert the loft though there is a possibility it
is exempt?

Unless you live in a conservation area or a listed building, or plan to
make dramatic changes to the roofline or the road facing side of the
roof, you are unlikely to require planing permission.

I need to find all building regs relating to this - I would appreciate
if people could give me pointers

All available here:

http://www.planningportal.gov.uk/england/professionals/en/1115314110382.html

The difficult bit will probably be the floor -

I was pleasantly surprised to find that in reality it was not that
difficult.

Obviously It will need
strengthening but do you have to take the roof off to get large beams
in?

If you are not adding dormers then you can probably do most of the work
from inside the roof space. You can remove a small section of tiles at a
suitable place on the front or back of the building that will allow you
to insert the longer beams etc.

How do you do the calculations?

How long is a bit of string? See my site to more guidance on this. There
is software available that can do all the required sums, but you do need
to do enough research and reading to know what information to feed in
first. Otherwise it will just help you design something wrong more quickly!

 

[manatbandq]

How does the law define a "habitable room" (in the loft)? I boarded my
loft out back in 1993. I was careful to make the loft ladder/stair
removeable (due to some clause in the regs which I forget). The two
Wickes' skylight windows I put in the roof in the roof are way above
the height-above-floor level of the current regs. Will this run me
into problems when I sell the house?

The more you do (floor, lights, windows, insulation, etc), the more of
a grey area it becomes. Just having a removeable ladder does not
prevent the room being "habitable", according to my local authority.
Only your local BCO can give you *his* interpretaion of the
regulations.

MBQ

 

[405 TD Estate]

Well in blue peter tradition, here is one I did earlier:

http://www.internode.co.uk/loft

Thanks for that I had a good read. The shower looks nice! I'll make
sure I print it out and put it in the 'loft' folder.

Where are you? The style of the bay wondows looks like Coventry...

 

[John Rumm]

Thanks for that I had a good read. The shower looks nice!
Ta!

Where are you? The style of the bay wondows looks like Coventry...

SE Essex...

 

[somebody]

Hi,

[snip]

I'd generally agree with the advice you've had so far, have plans drawn
by an architect who should instruct an engineer for you. These should be
submitted for approval by building control, and the work done under
their watchful eye.

The difficult bit will probably be the floor - Obviously It will need
strengthening but do you have to take the roof off to get large beams
in? How do you do the calculations?

The calculations will be part of the engineers remit. If you're going to
do it properly through building control, IME it doesn't matter whether
you can do the calculations, it matters whether you are qualified to do
so.

Any useful guides 'how to's' would be good.

My only 'tip' ...

If you're going to be putting in any steel work, consider how it will
physically be fitted. Three steels went in for our loft and typically
each would have been inserted through the building from outside. You
cannot fit a steel between two walls without knocking right through one
of them.

For two of the steels this would have meant a big crane 15m away at the
road. With the beams at 200Kg each, probably quite an expensive crane on
day hire.

For the third beam it would have meant removing the conservatory roof.

I asked the engineer about cutting/plating of the steels - he looked at
me as if I was mad ... "extra cost at the fabricators". The benefits
though are having steels which are reasonably man manageable, you can
work in your own time not to a schedule with equipment on hire, less
disruption to the whole building etc.

Hth
Someone

 

[405 TD Estate]

I asked the engineer about cutting/plating of the steels - he looked at
me as if I was mad ... "extra cost at the fabricators". The benefits
though are having steels which are reasonably man manageable, you can
work in your own time not to a schedule with equipment on hire, less
disruption to the whole building etc.

Hth
Someone

What - Do you mean cut the beams so you can get them up the stairs and
re-join them once there?

 

[405 TD Estate]

I'd generally agree with the advice you've had so far, have plans drawn
by an architect who should instruct an engineer for you. These should be
submitted for approval by building control, and the work done under
their watchful eye.

If all the beams run in one direction then working out strength /
deflection should be easy myself .

The problem would be how strong to make them?? I.e. whet woudl you
assume for worst case flor loading?

Maybe 12 adults all stood in the centre of the room?

If anyone knows the beam type and dimensions and the number of beams
used (or spacing apart) and the floor space I could back-calculate the
strength/flexibility of their floor and assuming it was build recently
and assume this strength is sufficient (as it will heve passed
building regs/approval)

 

[somebody]

What - Do you mean cut the beams so you can get them up the stairs and
re-join them once there?

Sort of...

One beam in a kitchen ceiling for a new load bearing wall - that went up
the stairs, inserted into the floor space from above and then bolted
together in situ.

Other two beams to replace the roof purlins were winched up the
scaffolding and into the loft through a new gable end window. They were
then inserted into position at both gable ends and bolted back together.

It will very much depend on whether you need any steelwork and where.

Having them cut and plated achieved a number of things...

- reduced weight to make them (in my case) man handlable.

- allows for insertion into two opposing walls without knocking right
through an outside wall.

- no need for a crane

Hth
Someone

 

[John Rumm]

If all the beams run in one direction then working out strength /
deflection should be easy myself .

The problem would be how strong to make them?? I.e. whet woudl you
assume for worst case flor loading?

For a domestic floor with joists spaced on 400mm c/c, you would often
use a loading of 0.8kN / m applied as a uniform load along the joist.

Depending on what other dead loads you impose on the floor, you may also
have to take account of point loads in addition to the uniform ones. For
example it would be quite common to include dwarf walls toward the eves
in a loft conversion that does not include a dormer. The weight of these
would then appear as a point load on each floor joist. If you say in
addition took our a purlin that was used to help support the rafters,
and replaced this with a dwarf wall, then the wall would become load
bearing, and not only would its weight be placed on the floor joists,
but so would be a proportion of the roof weight.

This was one of the things I alluded to in my original post. Doing the
calculations is not that difficult in many cases, but selecting
appropriate data to base the calculations on can be more difficult and
is obviously fundamental to arriving at a useful result.

If anyone knows the beam type and dimensions and the number of beams
used (or spacing apart) and the floor space I could back-calculate the
strength/flexibility of their floor and assuming it was build recently
and assume this strength is sufficient (as it will heve passed
building regs/approval)

Well, the normal spacing for floor joists is 400mm centre to centre. The
type of beam required will depend on the length and the loading[1]. The
simplest beam is a wood one made from ordinary C16 constructional grade
sawn timber. There are then a number of additional measures that can be
taken to increase the strength of the beam as required to meet the
performance requirements. These include:

1) Increasing the height and width,
2) using a higher stress grade of timber like C24,
3) using a pair of beams bolted together,
4) constructing a flitch beam (pair of wood beams bolted either side of
a steel plate).
5) Using steel sections in place of key beams

Designing your floor to have as many beams constructed using methods
near the front of the list will help keep costs down, and maintain
workability and speed of construction. However you may also need to take
into account headroom, which can dictate more exotic construction to
keep floor joist depth down.

[1] Building regulations stipulate the maximum amount of deflection that
is allowable in a floor joist (typically up to 0.003 times its length,
or 14mm whichever is smaller)

 

[Charlie]

The two

Wickes' skylight windows I put in the roof in the roof are way above
the height-above-floor level of the current regs. Will this run me
into problems when I sell the house?

Ken H

the alternative I believe is to fit fire doors throughout your house.

Could be cheaper than:
1. Moving the skyligh windows
2. Potential decrease in value of your house due to no building regs.

Just my thoughts!

Charlie