Loft, roofing timbers

[rosinante]

Hello again , bought a bungalow , it has a floored loft ,the floor is substantial and is hoisted with 6x2 timbers at 16 inch centres across the hallway walls , no more than 6ft clear span , I'm happy with that , however there was a poorly constructed room in the loft for a train set, to make space 2 of 3 collar ties were removed, these ran from purlin to purlin nailed only to a common rafter, thepurlins are 8x3 any the bungalow is about 36 ft long , no movement of the roof line can be seen internally or externally, I have replaced one tie and soon to replace the other , I have also put 6 collar ties at 7ft high , the rafters are 5x1.5 ins at 16 inch centres , if I were to put in a 4x2 tie at every rafter over the area the originals were , some 20 plus collars would that be sufficient to enable the long collar ties to be removed ? , my sketch sort of shows it , in summary 20 shorter and higher collar ties to replace 2 longer lower ones ,
Cheers

 

[gaz1]

you have no inside roof photo as this would have helped out

i cant tell from your pic what is there already to say whats best

is your side beams on there sides or straight pitched to the rafters ( rafters are your roof woods before your felt )

whats your height from the floor joists to the apex point

whats your width from beam to beam and what size are they 8x3 purlin beam

the purlin attached to the beam is at an angle whilst some are vertical and notched to the rafters the worst perlin beam are those on there sides as there not doing anything much



what are you after full access up there with flooring or intend to adapt it into something ?

 

[rosinante]

Hi , thanks for reply , the roof is as your pic , 8x3 purlin with support strits going down and inwards , these are 3x3 , 5x 1.5 ceiling joists as shown with 6x2 flooring joists added above them. Then 18mm t&g chipboard 8ftx 2ft flooring,
The ridge height is 8 ft ,
Nailed to a rafter and resting but not fixed to the purlin were collars right across the loft space , about 16 ft long,
The previous owner had removed those and put in a "room" for train set , it was dreadfully constructed , eg 4ft x 4ft plasterboard fixed with 3 screws, .
I am not concerned with a loft conversion but would like to use it for storage , the boarded floor area is approx 12ft x 20ft , all supported on 6x2 joisting which I believe was done by a competent chippy, I am in process of removing the walls, a term used loosely.
Can I dispense with the 16ft collar ties which as they are about 12 ft apart don't seem to be able stop the roof from spreading and fit 4x2 collars 12ins down from the bottom of the ridge board . There would be at least 16 of these , approx 40 ins long using Timco 6 mm hex head screws ,
Attached is a drawing left by previous owner there are subtle differences between as built and drawing, rafters are 16 in centres and not 18 ins , there were only 3 collars fitted the neighbours is same . Any advice welcome , thanks again

 

[gaz1]

is there any solid internal walls do the 6x2s sit upon as they should reach the front walls and sit on them as i cant tell from your drawing or the plans of this

make sure they do?

dont remove any woods until other woods are in place

if they are sat upon the outside wall and sat upon a solid built wall you can do alot more than you think

first off what you can construct is this called the attic

 

[gaz1]

Hi , thanks for reply , the roof is as your pic , 8x3 purlin with support strits going down and inwards , these are 3x3 , 5x 1.5 ceiling joists as shown with 6x2 flooring joists added above them. Then 18mm t&g chipboard 8ftx 2ft flooring,
The ridge height is 8 ft ,
Nailed to a rafter and resting but not fixed to the purlin were collars right across the loft space , about 16 ft long,
The previous owner had removed those and put in a "room" for train set , it was dreadfully constructed , eg 4ft x 4ft plasterboard fixed with 3 screws, .
I am not concerned with a loft conversion but would like to use it for storage , the boarded floor area is approx 12ft x 20ft , all supported on 6x2 joisting which I believe was done by a competent chippy, I am in process of removing the walls, a term used loosely.

from the info you have its not good enough for storage
6x2s added on top of ceiling joists would mean you have very little over hang onto the wall thats with normal ceiling joists of 3x2s or even 4x2s

so what thickness are your ceiling joists

at moment its reading like everything pulled up and save

adjust what you have so its properly sat on a solid surface and then reboard

 

[rosinante]

Hi yes the 6x2 s rest on the hallway walls and on joist hangers on the 9x3 binders which are set in gable wall and resting on bedroom wall . All partition walls are block construction the nearest in your pics is the habitable diagram,
I don't want a habitable room up there just the storage , the floor seems very solid, the 6x2s are on top of the joists , still 8 ft head room at ridge., cheers again

 

[rosinante]

Sorry not good at this , 6x2s are on top of ceiling joists resting on portion walls across hall way so max clear span 5 ft , then they extend to binder on joist hangers , very little load on thus bit as it is in the eaves , thanks for your patience,

 

[gaz1]

from what you are saying this is what you have from looking from above

the purple lines are your roof beams ( purlins )

the red lines are the binder beam from wall support to the apex wall

i presume the joist woods run across and are affixed using joist hangers to the binder beam



just check that the wall isnt a breeze block wall and also has a pad stone under the binder beam but not always done so as long as its concrete block wall

if yes to this then work can be done no problem as that floor is strong enough as it stands

for start off the woods can be done from the binder beams to the roof perlin or can go straight down and connect to the flooring itself

 

[gaz1]

dont remove any woods until you have done the top cross pieces to create the apex point

then you can remove them

height reference 20" is fine but 22" is even better

 

[rosinante]

Pretty much , the centre of the floor 6x2s are also supported by the hallway
walls , all are concrete block , will get on with the collars, 4x2s and 6 mm timco hex drive screws 80 mm long, , that's all I intend to do , then remove the long collar I replaced the long collars were remove some years ago and no movement has occurred , , thank you for you patience and answers , I will make sure there is more support than as built ,
Cheers Gaz

 

[gaz1]

cut the apex woods the same slope as the rafter woods as 4x2s become 5x2s when angled so 2 screws can be used per rafter

do each rafter all the way across

this is up to you fit wood from the floor joists up to the purlin beam make sure there level and call it a day at that if you want to board it out then do so

if you want to put extra insulation in do it before you fit the uprights

added note here yours is big enough to build a dormer onto the back

pic shows apex wood and joists overhanging concrete wall

 

[rosinante]

At this stage it is just the reinforcing of the basic structure with about 20 collar ties to replace the 2 long ones the previous owner had removed , this will allow access without ducking under , there is about 14 ft between the purlins and at least 20 ft from the gable to where the floor ends , a good size storage space, when I have cleared the crap timber and plaster board out I will take some pics , thanks again

 

[addjunkie]

I would suggest you get a proper bloke with letters after his name and insurance, to survey it, and detail recommendations to you.

That way once you alter it, if the roof collapses in heavy snow your buildings insurance should cover it

 

[Smallfry]

If the joists were properly connected to the rafters, you would not need the collars you want to remove. Would still not hurt to fit the ones up high as you propose

 

[gaz1]

at moment to a degree adding a little wood by making an apex is strengthening the structure close to the top

whilst adding the downward wood to the floor joists also strengthen the roof and also support the floor as well as they will share the weight between the purlin beams and also the binder beams

the adding effect it will to a degree stop the roof from splitting apart

those cross members might not seem much but they do hold the roof from splitting apart and to a degree they are an early warning that your roof is seperating

since some have been removed already the work that is going to be done will benefit the roof

 

[gaz1]

if you think his floor is bad try mine

x2 12 x4 beams with 3x3 beams we wasnt offered to fit stronger beams inbetween or connected into the walls