Dave wrote:

"The Natural Philosopher" wrote in message
...


What I would do is to seal up ancy celing cracks for draightproofing,
lay existing rockwool back , couner batten, and lay another layer at
right angles.


How does this cross battening affect the strength of the ceiling joists?
Elsewhere in the ng there is a suggestion that the original ceiling joist
(name?) are only just capable of holding up the plaster board ceiling.

Reason I ask, is that I am about to put more loft insulation and less junk
up there myself, at long last. :-))

I have also talked someone else out of boarding his modern loft with chip
board, but to use normal floor boarding instead if he must go ahead with
this idea of boarding. After all, it is a lot lighter.


Well leaving aside the issues of floor weight, if you cross joist the
loft with substantial timbers (at least 4x2. maybe 5x3 or 6x3 with long
section vertical) and actually screw (DO NOT NAIL into a flexible
ceiling - it WILL crack the plaster) every joist where they cross, you
will immensely strengthen the structure, even more so if the cross joist
can be rested on the walls at the ends, and even better if they are
connected by hangars and braces to the ridge and rafters.

Effectively you may double, treble or quadruple the stiffness, and
prevent bowing in the horizontal plane. You create a huge layer of space
into which pipes and so on can be lost inside decent insulation, and can
board out to a smooth finish for storage.

I'd say its a win win in every sense except time and cost.

The thing to watch out for is not supporting the new joists at the ends
- you will lose a lot of strength if you don't. Typically they will end
up at a hip or gable end of the house, you will have to work out how to
support them there and still leave (in the case of a hip) ventilation.





Dave