Hi John firstly thank you for your advice can you please answer these
questions for me -
Can you please let me know how these calculations are done so I can
calulate the correct loads with different materials and wood thickness
as I like knowing these things for future referance?
The second is an engineering one - if you used four cross beams as you
suggest then you would in effect have to support three sets of 3m beams
running front to back. This means that the front and back beams will be
carrying upto 12 of these joist ends (assuming 400mm spacing), and the
middle two will be carrying twice that. If you work on a loading of
0.8kN/m for your floor, that is 2.4kN per joist or 1.2kN downforce on
each end of the joist. This will give 14.4kN uniformly distributed
across the 4.5m span on your cross beams, and for the middle two this
would rise to 28.8kN. This is way over what would be an acceptable load
on a timber or even a flitch beam. So you would have to use heavy steel
beams here.
The more practical alternative is to insert 8x3" beams in between and
parallel to the existing ceiling joists and remove the tie beams
altogether. You could then insert a row of noggings between the new
floor beams which you fix to the ceiling joists.
sounds like a good plan as this would give me a higher cealing it is
quite large already though with a middle hight of around 3m so quite
allot to work with.
how would I go about this i.e how to support the cealing before the tie
beams are removed I guess you need to remove these before you put in
the 4.5m sections from the outer house walls to the center wall ? would
I attach the cealing jiosts to the perlins with metal ties and cut the
tie beams into sections to remove them ?
I am guessing this would pass the preasure to the middle wall and the
frount and back walls of our house the floor tie beam looks quite
large, is it not doing that much that it can be easyley removed as you
sirjest? (sorry my spellings not very good)
I have been informed that I could also hang 8"x3" jiost on the party
walls at 400mm centres using jiost hangers with the morter of the
current brick walls grinded out and then placing the hangers in the
wall and cementing them in is this a practical way of doing it ? and
would it give me the same amount of structual stregth i.e is it better
to hang jiost on the frount and back of the house or the two party
walls ?
if I do hang the jiost over the fround and back walls how would I
attach them to the walls just lay them on or what part should they be
succed to ?
thank you for your help with this in advance.
John Rumm wrote:
squelchy wrote:
Where are these part walls?
I live in a terrace house with a plan as below
-----------------------------------
----------------------------------- party wall 9m meter lengths
= / - / =
= / - / =
= / - / =
= / - / =
------....------------------....---- party wall 9m meter lengths
------....------------------....----
Ah, sorry I may have been getting the wrong end of the stick - I take it
when you said in your original post "it has two part walls", that was a
just a typo and you meant it has two "party" walls. It sounded as if you
has two bits of wall in the loft!
with limited ability to show drawings, below is where the tiled roof
section is tyed together with 4" by 2" wood 4.5m lengths bolted
together to form 9m lenth then bolted to the roof trusses
----------------------------------- party wall 9m lengths
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
------....------------------....--- party wall 9m lengths
------....------------------....---
You may find switching to a mono spaced font helps when dooing this type
of ASCII drawing - otherwise it is hard to make sense of unless we are
using the same font and software as you!
would I be able to put four jiost into the party walls and tie these
together with wood on jiost hangers to creat a grid like below and
remove the above roof ties and replace with metal banding ?
-----------------------------------
----------------------------------- party wall 9m lengths
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
------....------------------....---- party wall 9m lengths
------....------------------....----
There are two difficulties here. One is a practical one - have you got
the headroom to do this since you will be raising the whole floor by
about 10" minimum?
The second is an engineering one - if you used four cross beams as you
suggest then you would in effect have to support three sets of 3m beams
running front to back. This means that the front and back beams will be
carrying upto 12 of these joist ends (assuming 400mm spacing), and the
middle two will be carrying twice that. If you work on a loading of
0.8kN/m for your floor, that is 2.4kN per joist or 1.2kN downforce on
each end of the joist. This will give 14.4kN uniformly distributed
across the 4.5m span on your cross beams, and for the middle two this
would rise to 28.8kN. This is way over what would be an acceptable load
on a timber or even a flitch beam. So you would have to use heavy steel
beams here.
The more practical alternative is to insert 8x3" beams in between and
parallel to the existing ceiling joists and remove the tie beams
altogether. You could then insert a row of noggings between the new
floor beams which you fix to the ceiling joists.
would you recomend putting the joists through the wall or putting them
on heavey duty jiost hangers either by carving out the morter with a
grinders and remortering in the jiost hangers or bolting them to the
party walls with heavy duty wall bolts ?
Hangers are the favoured way these days. It saves creating a break in
the fire protection between the buildings and is less likely that the
ends will rot should the masonry get damp. You can get steel shoes
designed to go flat on a wall, which you fix with rawl bolts.
I do not rearly want to start romoving tiles from the roof as not
Not sure why you think you would need to?
looking to go the hole hog and fully convert just want a good solid
floor so no chance of damaging the plastering below.
This is why you normally space the underside of the new floor joists off
the existing ceiling level by a small amount. That way it is isolated
(it also keeps noise transmission down)
what size wood would be best and creat a solid floor i.e webbing and
jiosts ?
Assuming you want a floor that would pass building regs for a habitable
room:
You could use 4.5m beams that ran front to back on 400mm spacings,
resting on the middle wall and the front and back walls. For this you
eould need 8x3" C16 timber. (in fact you would probably make then a
little bit longer so that they overlap at the middle wall, and nail em
together with some builders band at the crosover.
Where the beams meet the front and rear walls you would need to cut the
ends at an angle to prevent the top of the beam hitting the tiles.
I appreciate that I should get a structual engineer to look over
everything but rearly do not want the expence. I cannot get building
Much depends on what you are planning to do with the space. Making a
storeage area is easy enough, however if you try to create a habitable
space it is also easy to build a deathtrap if you don't pay attention to
the details. This is one of the areas where it is very worthwhile
following the building regs. It will also make selling the place in the
future possible.
regs inviolved as they will not touch it as I only want to use my new
wooden fold away ladders that I fitted just a week ago hense after
It might be worth investigating if you could fit in a space saver stair.
--
Cheers,
John.
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