Boarding the Loft for storage

[docklandsuk]

Hi Everyone, my very first post so go easy

I'm currently in the process of loft boarding my friends loft, the size of it is 7.5m x 3.2

It's going to be used just for light storage, nothing really major going up there.

however after reading a few of the forum posts I'm a little worried now, the house i'd say is 1950/60s and it's a semi etc

Everything up in the loft looks pretty clean and new, there is a water tank mounted on extra timber above a partion wall below, and in the centre there is a chimney.

The Insulation is of the loose kind (sort of what they spray up via tube), I've managed to compress most of this ready to make way for the boards but theres a few wires going over the joists so would I be right in saying I need to use 20 amp junction boxes and make a small hole in the joists to hide these?

The Joists looking above them are about 50mm wide and they seem quite solid to walk on.

I would just like a little advice to see if I'm doing this right

Thanks

Peter

 

[JohnD]

there is a lot to be set by cross-battening with 50mm x 50mm timber or larger, at right-angles to the existing timbers. This spreads the load when you are standing or walking up there; gives more space for insulation, and also you can place then so that no boards are on top of cables or junction boxes.

Squashing down insulation is a bad idea as it reduces the effectiveness and leads to greater heat loss and expense on gas or electricity.

 

[docklandsuk]

Thanks for your reply, I've just taken some pictures, it's took me 2 days to do one side and junction box all the electrics etc.

Hope this gives you an ideal of what the loft is like, the insulation isn't compressed under the boards, i've just made it all neater as it was everywhere.

I don't want to be taking the boards back up to cross battern it, but I will if everyone says it does need it.

Where the chimney is a supporting wall running 3/4 of the loft length wise, their is also a supporting wall underneath the water tank again going 3/4 of the way across.


Here's four photos, two of the side I have done and two of the side not done, with the exposed joists and insulation.


ps need to finish the sides yet on the boarded side.

 

[breezer]

I would say dont put anything in the sides, as it may block ventilation, and PLEASE screw the boards down, i didnt and The x mrs breezer stood on the end, it tipped up and she went through the ceiling up to her armpits, its funny now, it wasnt at the time

 

[JohnD]

unusual to see a modern roof so roomy and without trusses. What sizes are the timbers?

I don't recognise the construction with those half-height triangulated things, are they on top of a wall?

was it built with the intention of using it as living space?

 

[docklandsuk]

Thanks for your replies,

I was going to put some very thin mdf/hardboard on the sides just to stop any of the insulation from blowing around, if I put this on the sides there would still be ventilation getting down the apex of the roof etc.

I'm not too sure about the trusses, I haven't removed anything, which timbers should I measure, the roof timbers, side or joists?

Everything seems pretty solid up there, there was a massive old fire place up there which must of been in excess of 40kg and I have removed this now (nearly killed me), that was resting on the centre beam running in long ways in the loft and this hasn't caused any problems that I know of, it had been there for many years according to my friend.

Any more advice would be appreciated.

 

[JohnD]

measure 'em all!

Do the side bits appear to have been added later?

 

[docklandsuk]

the sides bits have been there since day one, I've just been told that the house was built in 1967, I will measure everything on Sunday (my next day on the up there)

I was going to get some 1x1 timber strips and screw them on the sides as support for the mdf/hard board sheets that I'm going to put on the sides, I've used the round junction boxes for sorting the lighting cables out and passed them via small holes thru the joists (there wasn't that many cables)

The one thing that worried me was the shower cable, thankfully this didn't need moving as it runs between two of the joists, I did not want to touch this cable anyway and would of left it be, but as luck has it was in the the right place.

I've also marked on the boards where cables are passing in the joists and where the juction boxes are etc just for future reference.

Again this is only going to be used for light storage, it's not going to be converted to living space, the loft boards i have used at 18mm thick and I have staggered them like brickwork to spread the weight even etc.

so far so good i think, but keep the comments coming

 

[JohnD]

a point...

shower cables must not be buried in insulation. they are OK clipped to the joists and exposed to the air.

this is because they carry high currents and will overheat if insulated. The insulation halves (roughly) their current carrying capacity.

Lighting circuits are very lightly loaded and (typically, if run in 1.5mm cable on a 6A MCB) run at about a third of their capacity, so it does not matter if they are insulated.

a question....

How well do the boards fit the spacing of the "joists?" It is important not to have any unsupported joins.

 

[docklandsuk]

Hi John, the shower cable is clipped with small metal clips to one of the joists, it only comes into contact with insulation as it comes into the roof from the main consumer unit downstairs, must admit the cable is pretty thick stuff

The spacing of the joists is quite good, I've had to cut a few of the loft boards to size to match as some didn't line up as expected, I've also scribed around the timber supports coming down and the chimney, I've made sure screws are well away from cables, the tricky part is going to be the edges, might have to take a few boards up to enable me to scribe against the sides as it's the slot loft boards i've got.

I've made sure that no two loft boards finish next to each other (apart from the end runs etc)

 

[masona]

the sides bits have been there since day one, I've just been told that the house was built in 1967, I will measure everything on Sunday (my next day on the up there)

What you have is known as a solid purlin which should rest across the bearing walls and providing the purlin is not more than 1/3 of the roof rafters from the wallplate, very similar design to loft conversion

I was going to get some 1x1 timber strips and screw them on the sides as support for the mdf/hard board sheets that I'm going to put on the sides,

What I can't see is the cross battening as mentioned by JohnD, this will make it easier for floor laying plus cross ventilation as well & without having to notch out the ceiling joists for the cable/pipe

 

[IJWS15]

The insulation under the boards where you have compressed it will slowly expand up to the bottom of the boards leaving no ventilation gap. This WILL give condensation on the bottom of the boards and if chipboard this is not good.

You need to ensure a good ventilation gap between the top of the insulation and the bottom surface of the boards.

 

[Deluks]

The insulation under the boards where you have compressed it will slowly expand up to the bottom of the boards leaving no ventilation gap. This WILL give condensation on the bottom of the boards and if chipboard this is not good.

You need to ensure a good ventilation gap between the top of the insulation and the bottom surface of the boards.

Not necessarily.

 

[IJWS15]

"not necessarily" refers to what?

 

[mrcrow]

unusual to see a modern roof so roomy and without trusses. What sizes are the timbers?

I don't recognise the construction with those half-height triangulated things, are they on top of a wall?

was it built with the intention of using it as living space?

they are trussed members spanning the roof length and bear the sloping rafters
i had them in my town house in london