Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest

U value for walls between an Apt and unheated corridor

  • 01-09-2023 8:45am
    #1
    descol
    Registered Users Posts: 156 ✭✭


    Good morning Boards

    Looking for assistance from anyone familar with this topic - specifically the calculation formula as set out is Bldg Rgs 2012 TGD L.

    If you are familar with the formula - could you advise what values would be appropriate for Uo and Ru in a situation where the U value is required for the 215mm plastered block wall between the Apt and the corridor with the corridor having an Apt each side - i.e opposite wall is not an ext wall

    thanks in advance

    descol



Comments

  • #2
    sydthebeat
    Subscribers Posts: 41,915 ✭✭✭✭sydthebeat


    Do you mean subject to TGD L 2011 ??

    first question is why you wouldnt used the default value in the DEAP software? are you exhausting options to get the BER down?

    Ru for "Access corridor walls adjacent to unheated space" is 0.40 (assuming corridor above and below)

    The initial u value (or Uo) can be calculated if you know that the wall is actually made up as you've described, using values from table A1. im not sure if there is a prescribed default u value (Uo) in this situation?


    by my own calculations a 215 block wall with 15mm gypsum either side with internal horizontal surface resistance both sides = u value = 2.4

    adding a 0.4 Ru equates to a u value of 1.22

    the default in DEAP for this situation is 1.13

    so id be sticking with the DEAP default



  • #3
    descol
    Registered Users Posts: 156 ✭✭descol


    Hi Syd - always good to see your reply / advice

    As you note the DEAP software does or did have a drop down default of 1.13 for a 215 block wall to an exposed /semi exposed unhetaed circulation space.

    I have been on to the helpdesk about this and it would appear that it is preferabale to use the formula in the TDG - as it may improve the BER with a better U value for the wall.

    So, my query is - would it be correct to apply the U value of 1.13 to the Uo of the equation with the appropriate Ru being 0.40 ?

    If this is done then I get the U value for the wall of 0.78

    In the sample BER Assessment I am looking at this has a significant impact on the BER

    Would appreciate your views on this

    descol



  • #4
    sydthebeat
    Subscribers Posts: 41,915 ✭✭✭✭sydthebeat


    The default u value of 1.13 in deap includes the Ru resistance, unless you can find a Uo of 1.13 somewhere in the regs (I couldn't)

    As above, when I calculated the u value for your wall as described I come up with 2.4, which is quite a bit away from 1.13.

    Were the help desk about to provide you with a location to find this Uo?

    Bre 443 has an equation you can use to calculate it, but it's quite cumbersome, and I'm not very convinced that at the end of all this hard slog on your behalf you'll get a result much better than the default.



Advertisement