I have got a loft

[KeithHC]

Ok I have just moved into a 1970's built house and have a relatively clear loft space. Currently part boarded with an out of use water tank in one corner. Right I want to build my layout up there. I know that the ceiling joist will have to be increased in height by about 1/3 to take the floor and i will also put some extra cross braces in between the joist. Now my question without having to go to building control. Firstly i will not remove any of the roof stucture. The roof is tile on felt. What would be the best option to insulte the roof. The loft has insulation and i am going to increase this depth once the joists are altered.

 

Keith HC

[40034_Nick]

Ok I have just moved into a 1970's built house and have a relatively clear loft space. Currently part boarded with an out of use water tank in one corner. Right I want to build my layout up there. I know that the ceiling joist will have to be increased in height by about 1/3 to take the floor and i will also put some extra cross braces in between the joist. Now my question without having to go to building control. Firstly i will not remove any of the roof stucture. The roof is tile on felt. What would be the best option to insulte the roof. The loft has insulation and i am going to increase this depth once the joists are altered.

 

Keith HC

 

Celotex Between the rafters.. You will need to either plaster over it or a complete Vacuum seal. I did mine last year for exactly the same reason.. Still need to vacuum seal as abit of condensation is forming on the other side of the Celotex (Where warm air is hitting freezing air on the other side) but nothing major and only seems to happen below zero.. 

[APOLLO]

Important to keep the air flow around the roof timbers to avoid condensation and rot. I would seek expert advise. I had a Velux window installed by a local builder who advised me re air flow, insulation etc. By the way the Velux (4' x 4') really made a difference. Mine faces roughly north so only gets sunlight a short time in mid summer - no problems.

 

Your local council will advise re regulations. many do so via a website.

 

Brit15

[Kris]

When I did mine I left a 75mm air gap before adding 150mm of cellotex. Plasterboard and plaster on top. Building control were happy with that.

[Andrew P]

Hi Keith, Two bits of advice;

 

FIRSTLY buy a Fire Extinguisher, I was up in my loft many years ago and thought I could smell something funny, I turned around and the Florescent Light above the escape hatch was on fire, there IS only one way out normally.

 

Secondly, not sure if it will work, but I have a small Caravan De- Humidifier, that just takes Crystals, so no mains power., it worked fine in my Shed when I had condensation. I emptied it about every 3 days and the crystals lasted about 3 Months and only cost £4 a pack.

https://www.amazon.co.uk/CARAVAN-DEHUMIDIFIER-MOISTURE-SLIMLINE-MOTORHOME/dp/B00CKP5G16

[letterspider]

Ok I have just moved into a 1970's built house and have a relatively clear loft space. Currently part boarded with an out of use water tank in one corner. Right I want to build my layout up there. I know that the ceiling joist will have to be increased in height by about 1/3 to take the floor and i will also put some extra cross braces in between the joist. Now my question without having to go to building control. Firstly i will not remove any of the roof stucture. The roof is tile on felt. What would be the best option to insulte the roof. The loft has insulation and i am going to increase this depth once the joists are altered.

 

Keith HC

Celotex or equivalent - as thick as possible dependant on the width of your rafters but then you need to leave at least 50mm of airspace between the insulation and the felt to allow air circulation.

Then you need a good waterproof barrier over the Celotex

So you need to tape up the gap between the rafter and Celotex - I used adhesive 30mm width aluminium insulation tape and taped up any exposed bits of rafter still showing as well for good measure.

Then comes the waterproof barrier - Wickes does massive sheets of green polythene. You staple this to the rafters horizontally is easiest - starting from the top and over running each side about 50cm should you be continuing to insulate against your party walls.

Leave at least 15 cm hanging loose on the lower edge where you have to join to the next horizontal run of polythene.

At the boundary you want a double fold of overlapping barrier (a bit like a swiss roll)- stapled down and go over with tape as well for good measure. I found gaffer tape was best for this job.

Work your way all the way down to the joists.

Protect the membrane with 4mm hardboard or plasterboard etc.

 

It was getting quite expensive at this point but you should find yourself perfectly airtight.

 

You've now separated the cold air under your rafters from the warm air inside your loft. Problem then is where exactly does this air circulate to?

 

Does your roof have tile vents? If so consider to put horizontal pieces of reclaimed rafters at the top of the loft space (which you would insulate, waterproof and clad like the other rafters). This will allow the  air rising up between all the rafters to communicate with each other and pass out through the tile vents.

The air inside the loft is a problem becuse of the moisture from yourself and your house. The easiest solution is a Velux window as they have vents in the handle for air circulation and you also benefit from a lot of light. Otherwise you will need a de-humidifier, either chemical or electrical.

 

Finally worth getting in an electrician to run a spur to your loft of your main fusebox - about £50 for labour but it is properly certified.

 

The advice further down about an extinguisher is a good one as well.

[teaky]

Ok I have just moved into a 1970's built house and have a relatively clear loft space. Currently part boarded with an out of use water tank in one corner. Right I want to build my layout up there. I know that the ceiling joist will have to be increased in height by about 1/3 to take the floor and i will also put some extra cross braces in between the joist. Now my question without having to go to building control. Firstly i will not remove any of the roof stucture. The roof is tile on felt. What would be the best option to insulte the roof. The loft has insulation and i am going to increase this depth once the joists are altered.

 

Keith HC

Have you considered doing a proper loft conversion Keith?  By which I mean complying with Building Regulations.  That would create a "habitable room" which in most cases increases the value of your house.  (It frequently tops the list of what estate agents suggest people do rather than what most people seem to think.)

 

There will no doubt be people on here who disagree but if I was considering buying a house and someone had done a substantial piece of work like a loft conversion or extension I'd want to see the certificate from Building Control confirming that the structure was still sound and that any new work was up to scratch.  (Your insurers might take a similar view.)

[letterspider]

Celotex or equivalent - as thick as possible dependant on the width of your rafters but then you need to leave at least 50mm of airspace between the insulation and the felt to allow air circulation.

Then you need a good waterproof barrier over the Celotex

So you need to tape up the gap between the rafter and Celotex - I used adhesive 30mm width aluminium insulation tape and taped up any exposed bits of rafter still showing as well for good measure.

Then comes the waterproof barrier - Wickes does massive sheets of green polythene. You staple this to the rafters horizontally is easiest - starting from the top and over running each side about 50cm should you be continuing to insulate against your party walls.

Leave at least 15 cm hanging loose on the lower edge where you have to join to the next horizontal run of polythene.

At the boundary you want a double fold of overlapping barrier (a bit like a swiss roll)- stapled down and go over with tape as well for good measure. I found gaffer tape was best for this job.

Work your way all the way down to the joists.

Protect the membrane with 4mm hardboard or plasterboard etc.

 

It was getting quite expensive at this point but you should find yourself perfectly airtight.

 

You've now separated the cold air under your rafters from the warm air inside your loft. Problem then is where exactly does this air circulate to?

 

Does your roof have tile vents? If so consider to put horizontal pieces of reclaimed rafters at the top of the loft space (which you would insulate, waterproof and clad like the other rafters). This will allow the  air rising up between all the rafters to communicate with each other and pass out through the tile vents. (NOTE: You would add this bit of roof before you start to insulate!)

The air inside the loft is a problem becuse of the moisture from yourself and your house. The easiest solution is a Velux window as they have vents in the handle for air circulation and you also benefit from a lot of light. Otherwise you will need a de-humidifier, either chemical or electrical.

 

Finally worth getting in an electrician to run a spur to your loft of your main fusebox - about £50 for labour but it is properly certified.

 

The advice further down about an extinguisher is a good one as well.

[KevinWalsh]

If you go down the celotex route (which is a good idea), make sure you cut it outdoors and use a facemask with goggles, the dust from it is decidedly irritating and don't use an expensive saw as celotex turns a hard point saw into a round point saw very very quickly, I always use a cheap and nasty saw from poundland for cutting it.

[chris p bacon]

Ok I have just moved into a 1970's built house and have a relatively clear loft space. Currently part boarded with an out of use water tank in one corner. Right I want to build my layout up there. I know that the ceiling joist will have to be increased in height by about 1/3 to take the floor and i will also put some extra cross braces in between the joist. Now my question without having to go to building control. Firstly i will not remove any of the roof stucture. The roof is tile on felt. What would be the best option to insulte the roof. The loft has insulation and i am going to increase this depth once the joists are altered.

 

Keith HC

If you search lofts here you'll find lots of advice.

 

Personally, I think this statement

 

my question without having to go to building control.

 

Is just plain wrong 

 

Building control are there to help, and you definately need advice for what you propose to do.  For a start increasing the ceiling joist by a 1/3rd is not sufficient for a floor, what you most probably have is a trussed roof which means that the ceiling joist, (which is there to hold up the ceiling below and to tie the wall plates together, and in a triangular form support the roof) was never intended to provide structural support, it is possibly just 35mm x 70mm whereas a typical floor joist now is 47x200 (depending on span). Not only do you have issues over insulation and ventilation to overcome but the most important thing is Fire. 

Without seeming to sound like a negative doom & gloom merchant, lofts are the void between the ceiling and the roof and not a room space, they'll be many diyers here saying go ahead and don't worry but they won't be the ones trying to sell in a few years time. 

[rockershovel]

Re #5, a good many years ago my brother-in-law managed to miss his footing in the loft, and put his foot squarely on the laths of the ceiling below. Be assured, there is more than one way out of a loft if you REALLY need one....

 

Our house has a boarded out loft, with boards spanning the ceiling joists. Then again, like most early-1930s houses they are much larger than modern ones, they carry the full weight of the lath-and-plaster ceilings - MUCH heavier than modern ones - and the internal walls are all brick (not cinder block and certainly not stud-and-board)

[hayfield]

If you are going to use the loft, then do it properly

 

1 Do comply with building regs, they are there to protect you and others

2 Make sure any insulation/uilding work does not cause damage to the roof (rot etc) or ceilings etc

 

Good luck

[RFS]

You don't just need a fire extinguisher in the loft but also well-maintained fire alarms in the house as well.

 

Also make sure you don't do anything in the loft that might invalidate your house insurance policy. If you have a fire in the loft that does serious damage, and the cause was due to changes you had made in breach of Building Regulations, your insurance company could reject the claim.

[KeithHC]

Thank you all for the advice a lot of which will be taken on-board. The roof construction is not the many triangles so the ceiling joists are larger than my last property built in 2010. My thoughts on the increase by 1/3 was based on what I remembered from college when doing civil engineering. There was me working on the M25 and being taught all about house building. Electrics will be done proffesionally especially as at the moment there is a lighting system that can only be on when the upper landing lights are on! I will talk to building control just to ensure its done correctly. Oh yes a fire extinguisher is a must. I am also looking into at least two velux windows and both will be north facing which is also at the back of the house. Also the roof has some large vents already installed so I will ensure there is the airflow.

 

Once again many thanks.

 

Keith

[larryblag]

I've recently moved into my loft. Bungalow built 1982, the joists aren't particularly thick due to modern(ish) building methods but with the extra timber I've put in and the boarding which spans the entire middle section - I'm happy that it's ok. Plus the main area I'm working (and walking) in is directly above partition walls so they are bearing the load. The layout will sit on the "vee" between the joists so thats not loading the ceiling either. I did get some advice beforehand though and would advise anyone to do the same.

[The Johnster]

Have you considered doing a proper loft conversion Keith?  By which I mean complying with Building Regulations.  That would create a "habitable room" which in most cases increases the value of your house.  (It frequently tops the list of what estate agents suggest people do rather than what most people seem to think.)

 

There will no doubt be people on here who disagree but if I was considering buying a house and someone had done a substantial piece of work like a loft conversion or extension I'd want to see the certificate from Building Control confirming that the structure was still sound and that any new work was up to scratch.  (Your insurers might take a similar view.)

 

This is good advice; it is my opinion that in any case a model railway is best situated in the habitable part of the property, where it is heated and ventilated properly, not to mention easily accessible.  This viewpoint is 'informed' by a layout in the loft of my parent's house in my teens, many, many, years ago, which had been 'converted' (to the extent that some chipboard flooring had been nailed down) by my father, an inveterate bodger whose only excuse for not being a complete cowboy was that he already had a job.  The temperature extremes ripped the railway to pieces with expansion and contraction, and there were only a very small number of days when it was not either too hot or insanely cold up there...  I learned from this to never have a railway in a loft, shed, cellar, or any other space that was not a proper part of the living area of the property, and would advise anyone else to do the same.

[chris p bacon]

I've recently moved into my loft. Bungalow built 1982, the joists aren't particularly thick due to modern(ish) building methods but with the extra timber I've put in and the boarding which spans the entire middle section - I'm happy that it's ok. Plus the main area I'm working (and walking) in is directly above partition walls so they are bearing the load. The layout will sit on the "vee" between the joists so thats not loading the ceiling either. I did get some advice beforehand though and would advise anyone to do the same.

This is not meant in anyway critical but may I ask who you sought advice from.

 

What you describe is a typical truss roof which can in no way bear any weight apart from what it was designed to do. The reason the timbers are smaller in size is because the calculated loading is taken upon the rafters which are connected by braces to form a triangle. 

 

I am not against the use of lofts,  if they are made into a habitable space conforming to building regulations they can add amenity and value to a property, but done incorrectly they can be something approaching a nightmare with countless problems stored up for the future. 

[young37215]

This is not meant in anyway critical but may I ask who you sought advice from.

 

What you describe is a typical truss roof which can in no way bear any weight apart from what it was designed to do. The reason the timbers are smaller in size is because the calculated loading is taken upon the rafters which are connected by braces to form a triangle. 

 

I am not against the use of lofts,  if they are made into a habitable space conforming to building regulations they can add amenity and value to a property, but done incorrectly they can be something approaching a nightmare with countless problems stored up for the future. 

I echo the above comments having recently had completed a storage room in the loft of my modern bungalow which involved part removal of the triangular trusses. The design was completed by a qualified Structural Engineer who confirmed compliance with current Building Regulations. As insulation I used 100mm Celotex for the walls and YBS multiquilt for the roof because height was at a premium. YBS not cheap but seems very efficient. As others have counselled, electrics were professionally installed and comply with current regulations. Radiators connected to central heating system have also been added. A good job was not cheap but I now have a structurally sound and fully insulated 42 square metres of modelling space.

 

Important choice of wording 'storage room' to avoid allegations from money sucking Council that I have added habitable space to my property and increased rateable value!

[teaky]

I've recently moved into my loft. Bungalow built 1982, the joists aren't particularly thick due to modern(ish) building methods but with the extra timber I've put in and the boarding which spans the entire middle section - I'm happy that it's ok. Plus the main area I'm working (and walking) in is directly above partition walls so they are bearing the load. The layout will sit on the "vee" between the joists so thats not loading the ceiling either. I did get some advice beforehand though and would advise anyone to do the same.

"...so thats not loading the ceiling..." - it is actually because the load is spread by the structure.  The ceiling joists do more than just hold the ceiling up.

 

From your description, it sounds like you have a truss rafter roof (a triangle with W-shaped bracing).  If that is the case then you should not view the structure in terms of separate components (rafters, ceiling joists, connecting braces and so on) but as a series of single, triangulated elements.  Each element is designed to spread the loads and stresses.  If a traditional roof was constructed using individual rafters and ceiling joists of the same timber it would not be strong enough, but when combined into a trussed rafter it becomes much stronger.  In addition, the horizontal and diagonal bracing pieces which you no doubt also have are critical, functional components which tie everything together to allow the roof to resist the wind.

 

In sizing the roof timbers the calculations allow for the basic support requirements plus wind resistance plus storage plus one person accessing that storage plus a sensible safety margin.  By putting a layout in the loft, boarding, your weight and a guest(s) plus whatever you have stored up there you are using that storage+margin part of the calculations.

 

Obviously, I don't know exactly how your house is constructed but don't assume that just because the partition walls look like they support the roof that they actually do so. Presumably your advice came from someone qualified to do this, so I assume you're happy.

 

Please don't take this as criticism, I am posting this more to warn anyone considering converting their loft that they need to check things through and not assume it is OK to put down boards and start a layout.  The topic of loft conversions has cropped up a number of times over the years and quickly seems to polarise into those who think everything should be done in accordance with Building Regs and those who perhaps think the Regs are OTT and "I've been using my loft this way for years and nothing has gone wrong so it is OK".  It is probably obvious where I stand but my feeling is that no one should do anything like this in ignorance.  If someone chooses to take the simple route then they should do so understanding that there are risks.

[teaky]

I echo the above comments having recently had completed a storage room in the loft of my modern bungalow which involved part removal of the triangular trusses. The design was completed by a qualified Structural Engineer who confirmed compliance with current Building Regulations. As insulation I used 100mm Celotex for the walls and YBS multiquilt for the roof because height was at a premium. YBS not cheap but seems very efficient. As others have counselled, electrics were professionally installed and comply with current regulations. Radiators connected to central heating system have also been added. A good job was not cheap but I now have a structurally sound and fully insulated 42 square metres of modelling space.

 

Important choice of wording 'storage room' to avoid allegations from money sucking Council that I have added habitable space to my property and increased rateable value!

Good point.  I was tempted yesterday to edit my first post but things seemed to have moved on quickly.

 

It is a toss up I suppose.  If the room has a proper staircase and complies with Building Regs in terms of insulation, fire resistance etc. then you will be able to call it a habitable space.  This may take you into a higher council tax bracket but it will also add value to your house.  If you use a loft ladder then it is not a habitable space but will be slightly more awkward to access for some people.  It should still add value but not as much as an additional bedroom would but then it might be cheaper to do in the first place.

[teaky]

I echo the above comments having recently had completed a storage room in the loft of my modern bungalow which involved part removal of the triangular trusses. The design was completed by a qualified Structural Engineer who confirmed compliance with current Building Regulations. As insulation I used 100mm Celotex for the walls and YBS multiquilt for the roof because height was at a premium. YBS not cheap but seems very efficient. As others have counselled, electrics were professionally installed and comply with current regulations. Radiators connected to central heating system have also been added. A good job was not cheap but I now have a structurally sound and fully insulated 42 square metres of modelling space.

 

Important choice of wording 'storage room' to avoid allegations from money sucking Council that I have added habitable space to my property and increased rateable value!

I'm interested in your use of YBS multiquilt (Superquilt?).  What sequence of layers did you use, how deep are your rafters, how much depth of insulation did you save and do you know the U value achieved?  When I looked at this recently it didn't seem to be saving me very much depth.  Maybe I made an error somewhere or it may simply be down to the depth of rafters.

[Bernard Lamb]

 

 

Important choice of wording 'storage room' to avoid allegations from money sucking Council that I have added habitable space to my property and increased rateable value!

Back in the period when we paid rates that would have been the case and notification was required when the work had been signed off. 

Now we have council tax and this was fixed at a certain date and will not vary upon any changes or enlargements to the property.

What will happen in the future is pure guess work.

The term you use 'storage room' might not go down too well with your insurance company in the event of a claim. 

From my experience the biggest problem with a loft conversion is the modification required to fit a legally compliant stair. It is not just making it compliant it also make access far more comfortable.

Also a check as to any changes to doors regarding fire resistance would be worthwhile. Make it into a three story house and you will find a lot of extra work is needed.

Bernard

[edcayton]

They might impose a tax on windows.

 

Ed

[chris p bacon]

They might impose a tax on windows.

 

Ed

Move to Apple.....

[The Stationmaster]

Good point.  I was tempted yesterday to edit my first post but things seemed to have moved on quickly.

 

It is a toss up I suppose.  If the room has a proper staircase and complies with Building Regs in terms of insulation, fire resistance etc. then you will be able to call it a habitable space.  This may take you into a higher council tax bracket but it will also add value to your house.  If you use a loft ladder then it is not a habitable space but will be slightly more awkward to access for some people.  It should still add value but not as much as an additional bedroom would but then it might be cheaper to do in the first place.

 

When we had our (newly built) house assessed for Rateable Value the Assessing Officer (or whatever her job title was) explained that assessment is based on what they see at the time of assessment (hence I don't have a garage for rating purposes because it hadn't been built at that time).  However when the property changes hands any changes of which the Planning Authorities are aware are supposed to be taking into consideration and the Rateable Value should be reassessed.

 

Our original plans included the roof space as habitable space but for various reasons I took the staircase out of it, and associated fire resistant doors out of the plans and simply had a loft ladder fitted - advising the planning people accordingly and stating that the roof space would only be use as an attic for storage.  This was checked by the Building Inspector on his sign-off visit and also checked by the Assessing Officer on her visit and she explained that if I had followed my original plan to have a model railway up there it would count as habitable space and would not only count as that for rating assessment purposes but should have the correct access for habitable space.  Things might have changed since then but I suspect they haven't.  (incidentally my 'attic' has a full load bearing floor, is fully plastered, has lighting, a couple of gable windows and two Velux windows but it is still an attic - and that shows!)

 

Edit to correct typos