How much do drywall screws impact insulation value of a wall?

[ADLIan]

The 0.006 W/m2K only applies to the wall construction outlined in the 1st post. Change the thickness of either layer of insulation and the number will change. Still nothing to worry about!!

[Pocster]

Guys 

 

How much do drywall screws impact insulation value of a wall?

 

Answer : (expletive deleted) all 

[Iceverge]

I don't have access to the ISO files so I was just calculating it on my mobile/in my head. 

 

A quick play with PHPP (note the display can't show small % so both inputs look the same) . Assuming steel screws and  a total steel area of 0.02% even for the bigger screws as the thread portion won't conduct much. 

 

Without screws:

 

 

With Screws:

 

About 0.04W/m2K of a difference. I'm not sure @ADLIan how I'm more than an order of magnitude out from your 0.006 W/m²K.  

 

@nostos156 The worst case of my numbers it's still only 6p of difference per m2 per year. 

 

 

 

 

 

 

[ADLIan]

Because you are only altering the area weighted average u-value. The correction for fixings is a separate calculation (based on type of fixing, number of fixings and construction/insulation thickness of the element) that is then added to the basic u -value.

[nostos156]

On 04/08/2023 at 19:07, ADLIan said:

Because you are only altering the area weighted average u-value. The correction for fixings is a separate calculation (based on type of fixing, number of fixings and construction/insulation thickness of the element) that is then added to the basic u -value.

 

Is this because the corrections take into account things such as the fastener not being exposed on both ends but embedded, air film, the time it takes for the heat to cross through the fastener and back, etc?

 

Apparently these things make a big difference when applied and not just calculating basic U-values.

 

Edited August 6, 2023 by nostos156

[Andehh]

You guys are going to shit yourselves when you realise the impact on insulation when you open your front door on a cold or windy day!! 😂

[joe90]

5 minutes ago, Andehh said:

You guys are going to shit yourselves when you realise the impact on insulation when you open your front door on a cold or windy day!! 😂

Which is why I built an enclosed porch 🤷‍♂️(air lock).

[ProDave]

7 minutes ago, Andehh said:

You guys are going to shit yourselves when you realise the impact on insulation when you open your front door on a cold or windy day!! 😂

With a properly air tight house, very little draught enters the house when you open just one window or door.

[SteamyTea]

1 hour ago, ProDave said:

With a properly air tight house, very little draught enters the house when you open just one window or door.

Very true.

My thermometer is on the wall next to my window.

It is now 10:25 AM and the display is showing 22°C

I shall open the window and come back in a while and see how much the temperature has dropped.

 

15 minutes have passed, the thermometer is showing 21°C.

This is a small room as well. 3.5m by 2.5m.

 

Thought I better look at the OAT as well, 10:25 7.2°C, 10:40 7.8°C (the sun has come out and it has stopped raining)

Edited February 25, 2024 by SteamyTea

[SteamyTea]

Here is a chart covering the last hour of having the window open.