DIY two storey extension

[Chickenski]

Many apologies to Alpcon. No offence was meant.

I have abundance of intelligence and this is a reason why I am doing it myself. What intelligence has to do with being a woman, is another question.
I have first class technical knowledge (both academic and practical) to carry out this project myself.The reason I turned to this forum is to get the advice on building regulations. These are sometimes without any logic.
For example: exit doors opening inside will block fire escape for a family of 2 adults and 3 children. Anywhere in the world building regulations would not allow that and so they stipulate that exit doors always open out.

To moderator: telling me to get the builder is NOT advice. If this was advice your forum would have no right of existence. Surely you can see that?

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[Deluks]

the poster has offered advice to you. If you do not agree or like the advice given please do not resort to insults towards the poster who is giving up his valuable time to try and assist you.
any similar posts will be deleted

She asked if he had a builders bum, followed by a LOL, hardly likely to insult Alpcon, unless he is seriously oversensitive and prone to random bouts of crying.

 

[Chickenski]

Just as you thought you put me off my project, I am back!
Work is going fine and we have now reached the roof. Conquered many problems with steel, too-big windows, bad weather etc

We now need to extend existing hipped roof and build another smaller one joined to it. hmm...

Our old wall plate sits on a solid wall so obviously, because new cavity wall is much thicker, new wall plate is not in line.

How do we align them so we can retain the same angle of the slope.

I will be GRATEFUL for advice please.

 

[noseall]

build the new internal wall higher, thus setting the wall plate higher, thus aligning new-existing.

it does mean the ceiling will be higher though.

 

[Chickenski]

Thanks Noseall!!

I will try although I really did not want to have different levels of ceiling. This extension will not create more rooms; it will enlarge existing ones.
I already have several (eight!) RSJs in the new part, with some of them sticking out like an eyesore...

Is there no other solution so I can keep the same level?

 

[andywatson]

Wouldn't an internal ceiling be easy enough to lower if you wanted consistent heights?

OK you would have a block of empty "wasted" space above the new ceiling, but would achieve the look you were after

 

[Chickenski]

Thanks, we will probably have to go with that.

I am ordering timber for the roof today. It comes in increments of 60cm. Meaning 4800mm or 5400mm. We have exactly 4600mm inside plus 100mm on each side for wall plate. Is it safe to assume 4800mm will be enough or go for longer ones??? Do joists overhang the cavity?

Will be great to get the answer asap

 

[noseall]

the joists can be cut off flush with the back of the wall plates if necessary.

they are best cut this way, as it allows the cavity insulation up past the joist ends, and to eventually meet up with the loft inso'. i know the rafter ends will still be in the way but at least it's one less obstacle.

 

[Chickenski]

Thanks again Noseall and andywatson.

Another problem. We have just discovered that the ceiling joists in the loft run front to back of the house. Do we continue the same way on the new floor? Or do we run them arcoss the house? Would running them different way to existing be acceptable by BC? What is the benefit of either?
In my non-professional view it is better to have them across the house so they are strengthened by being attached to rafters. Am I right?
I am intending to use the loft for so need to strengthen the floor. Would 7x2 joists be sufficient?

Dimensions are: existing house 7400x5200, rear extension 4500x5200. Small detached house with hip roof to be continued in the same manner on new part. Full ground floor extension with L-shaped on the first floor (BC recommendation so the neighbours enjoy unrestricted 45 degree vision from 1st floor bedroom...)

Also, I would like to send you a photo of what is happening. How do I insert one into this message? I think the only way is to email to admin and they post it on my behalf?

Would having a picture help?

 

[noseall]

you would usually run the joists the same direction as the rafters, on a standard gable roof.

these joists not only deal with the ceiling plasterboard and a little light loading, but more importantly, provide lateral restraint for the rafters.

on a hipped roof things are slightly different.

run the joists in the same direction as the majority pitch. in other words, the hip side with any amount of ridge.

you continue running the joists until about 600mm from the end hip, then run some short joists at right angles from the final joist. these short joists will be fitted to the rafter ends of the end hip.

hope this makes sense.

i would imagine you will need 9" x 2" to cover a 5m span. set at 400mm c/c.

 

[Chickenski]

As usual very very helpuf Noseall!

If the joists on existing house run from to back of property, do I need to extend them (I am extending existing roof) until the end of hip?? I could do that as I can use existing wall plate on the end of the hip. Do I bolt them together or just rest them on the wall plate next to existing ones?
Then run perpendicular joists to support the hip? Am I correct?

Will rafters on the majority hip have no restraint from joists at all?? How do they remain stiff and in place???

Logically, it would be better to run across to support the rafters.

 

[Chickenski]

Good afternoon!

dismantling hip roof and extending it in the same form. Can I leave existing hip rafters in place or should I remove them? They should not be in the way at all as new rafters would be joined to new ridge board. The roof will end with another set of ridge rafters to create new pitch.

What is the best way of connecting ridge board?

Any suggestions will be welcomed as I am struggling a bit.....

Thanks

 

[noseall]

the ridge boards don't necessarily need connecting, as the new rafters will be supporting the new ridge.

they could be joined though by using either a pair of plywood plates or a scarf joint. don't forget to allow for the roof pitch, when fixing any plates.

if you don't remove the hip blades, and the hip blade is slightly 'out of pitch' (which they can be), then you may notice a hump or dip in the new roof.

hip roofs are quite difficult to build, and you may want to seek professional help.

are there any purlins specified?

 

[noseall]

p.s.

don't forget, the hip blade (rafter) will be a completely different pitch to the rest of the roof.

 

[Chickenski]

Thank God for Noseall!!!

My architect specified trussed roof. I decided to go for cut version because we have another small hip roof joined to it and it all seemed too complicated.

Original purlins are odd size: 150mm x 80mm so I will probably go for 6x3 if I can find such size!

I am a bit concerned that if I take out hip blades the whole roof will spread out??? How do I support it?

Reference ridge board, if I do not connect it or connect it with ply plates will the new/old part of roof need any other reinforcements? Or will purlins be holding everything in place?
What is a scarf joint?

I am really grateful to you for your help. I am a female doing all this by myself and will be fantastically proud of myself if I manage to pull it off....