Danelaw vs Cromar vent 3

[Paul84]

Hi people,

 

What is the better choice here, Danelaw underlay DLR120 or Cromar Vent 3 light 95GSM? 

 

I'm doing a 8.5m x 4m lean to roof with 20degree pitch for my extension. 

 

Would a thicker DLR150/180 be worth the extra money or is it just a waste.

 

Thanks people.

[epsilonGreedy]

On 26/03/2021 at 13:17, Paul84 said:

Would a thicker DLR150/180 be worth the extra money or is it just a waste.

 

 

One deciding factor could be the speed of your project and how long the underlay will be exposed to the elements. At this time of year 4 months exposure to sun light would push the UV durability specs of underlay. In the winter frost action on a fancy laminate underlay is a real risk according to another forum member.

 

I would also be concerned about the cumulative effect of wind on an exposed underlay including uplift caused by open window apertures that lead to positive pressure in gusts and negative pressure on the downwind side of a ridge, hip or verge. I guess that your extension is single story and more protected from wind than a main roof.

[PeterW]

On 26/03/2021 at 13:17, Paul84 said:

I'm doing a 8.5m x 4m lean to roof with 20degree pitch for my extension. 

That’s very shallow. What tiles have you got that work that low ..??

 

I’d be making sure that the laps are taped and that you have a suitable overlap - 4-500mm wouldn’t be unreasonable. 

[Paul84]

Hey,

Marley double Roman tiles are planned, I've got the Marley rep looking at my plans this week to give me a spec list. 

Redland also do a double Roman which goes to 20degrees. So plenty choice. 

 

Guess the underlay doesn't really matter then. Thickest for cheapest.