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Skew Fast -
warm roof fixing

Installation speed of a nail with load capacity of a screw

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Skew Fast 1
What is Skew Fast?

Introduction

The pitched warm roof method is an established method of retrofitting insulation. By placing insulation over the rafters, the whole of the loft area is kept warm and dry.

Skew Fast is used to fix the counterbattens over the insulation and the counterbattens effectively become the rafters.

With a very small effective core diameter Skew Fast can be used in timber widths of 30 mm or below, while still conforming with CP112:1972, something not possible with a conventional nail of equivalent length.

How it’s made

Special features

  • Available in 304 and 316 austenitic stainless steel.
  • Allows insulation to be installed outside of existing home structure.
  • Can be installed without power.
  • Available in 5 mm length increments.
  • Provides structural stand-off.
  • Less disruption compared to other repair methods.
  • Highly durable material.
Skew Fast 2

Download Skew Fast info

  • Requirements
  • Wind Loads
  • Sliding Loads
  • Tile Weights
  • Tooling

When specifying the fixing detail for warm roofs, there are two elements that need to be considered:

  1. The wind loading is determined by the location of the structure, the form of the surrounding land and the height of the structure.
  2. The sliding load is also necessary to assess because of the crushable nature of the insulation material. The factors that determine the sliding loads are the thickness of the insulation, the slope of the roof and the weight of the roof covering materials.

The fixing design will need to address all these factors.

Within the UK, C.P. 3 Chapter V, Part 2, 1972 and amended in 1986, describes a wind exposure chart dividing the country into three wind zones:

Wind Zones A, B and C are defined as follows:

  • Wind Zone A – Basic wind speed up to 44 m/s
  • Wind Zone B – Basic wind speed of 44 – 52 m/s
  • Wind Zone C – Basic wind speed over 52 m/s.

The wind suction table, below, takes account of the effects of the slope of the land within 1km.

Where the structure height is over 15m the fixing density must be factored by 1.52.

Wind ZoneSlope of Land
within 1km		Suction
kN/m²		Batten Thickness – mm
253850

A

Up to 1:202.54.03.02.0
1:20 to 1:12.53.56.03.52.5
No Limit4.77.55.03.5

B

Up to 1:203.56.04.03.0
1:20 to 1:12.54.37.04.53.5
No Limit6.611.07.05.5

C

Up to 1:204.16.54.53.0
1:20 to 1:12.55.08.05.54.0
No Limit7.612.58.56.0

Below are the tables we use to calculate the density of Skew Fast that are required to resist sliding loads imposed on the roof. These are calculated using British Standard tables, and take into account the weight of tiles, the pitch of roof, the insulation thickness and whether there is a stop batten installed at the eaves level. The number that is found in the table corresponds to the number of Skew Fast required per square metre to resist sliding loads. Please note that wind loads MUST also be taken into account.

The first three tables below show the impact of using different insulation depths WITH a stop batten installed at eaves level.

Insulation Thickness 36-50mm (WITH STOP BATTEN)
Laid Tile Weight
kg/m²		Roof Pitch
20°30°40°50°60°70°80°90°
103.04.04.03.02.01.01.01.0
203.54.54.54.03.02.02.02.0
303.55.05.05.04.03.03.03.5
404.05.56.05.55.04.04.04.5
504.56.06.56.55.55.05.05.0
604.56.57.07.06.56.06.06.5
705.07.08.08.07.57.07.57.5
805.58.08.59.08.58.08.58.5
906.08.59.59.59.59.09.59.5
1007.59.010.010.510.510.010.510.5
Insulation Thickness 51-75mm (WITH STOP BATTEN)
Laid Tile Weight
kg/m²		Roof Pitch
20°30°40°50°60°70°80°90°
103.04.04.03.02.01.01.01.0
203.54.54.54.03.02.02.02.0
303.55.05.05.04.03.03.03.5
404.05.56.05.55.04.04.04.5
504.56.06.56.55.55.05.05.0
604.56.57.07.06.56.06.06.5
705.07.08.08.07.57.07.57.5
805.58.08.59.08.58.08.58.5
906.08.59.59.59.59.09.59.5
1007.59.010.010.510.510.010.510.5
Insulation Thickness 76-150mm (WITH STOP BATTEN)
Laid Tile Weight
kg/m²		Roof Pitch
20°30°40°50°60°70°80°90°
105.57.57.05.54.02.02.02.0
206.08.58.07.05.53.53.03.0
306.59.09.58.57.05.55.04.0
407.510.010.510.09.07.07.06.0
508.011.012.011.510.59.08.58.0
608.512.013.013.012.010.510.59.5
709.013.014.015.013.511.011.010.0
809.514.015.017.015.014.013.011.0
9010.015.016.018.017.016.014.012.0
10010.516.017.019.019.017.016.015.0

The second set of three tables shows the impact of using different insulation depths WITHOUT a stop batten installed at eaves level.

Insulation Thickness 36-50mm (WITHOUT STOP BATTEN)
Laid Tile Weight
kg/m²		Roof Pitch
20°30°40°50°60°70°80°90°
103.04.04.03.02.01.01.01.0
203.54.54.54.03.02.02.02.0
303.55.05.05.04.03.03.03.5
404.05.56.05.55.04.04.04.5
504.56.06.56.55.55.05.05.0
604.56.57.07.06.56.06.06.5
705.07.08.08.07.57.07.57.5
805.58.08.59.08.58.08.58.5
906.08.59.59.59.59.09.59.5
1007.59.010.010.510.510.010.510.5
Insulation Thickness 51-75mm (WITHOUT STOP BATTEN)
Laid Tile Weight
kg/m²		Roof Pitch
20°30°40°50°60°70°80°90°
105.57.57.05.54.02.02.02.0
206.08.58.07.05.53.54.04.0
306.59.09.58.57.05.55.56.0
407.510.010.510.09.07.07.57.5
508.011.012.011.510.59.09.59.5
608.512.013.013.012.011.011.511.5
709.013.014.015.013.513.013.513.5
809.514.015.017.015.015.015.515.5
9010.015.016.018.017.017.018.018.0
10010.516.017.019.019.019.020.020.0
Insulation Thickness 76-150mm (WITHOUT STOP BATTEN)
Laid Tile Weight
kg/m²		Roof Pitch
20°30°40°50°60°70°80°90°
1011.015.014.011.08.04.04.04.0
2012.017.016.014.011.07.08.08.0
3013.018.019.017.014.011.011.012.0
4015.020.021.020.018.014.015.015.0
5016.022.024.022.021.018.019.019.0
6017.024.026.026.024.022.023.023.0
7018.026.028.030.027.026.027.027.0
8019.028.030.034.030.030.031.031.5
9020.030.032.036.034.034.036.036.0
10021.032.034.038.038.038.040.040.0

The following tile weights can be used as a guide for quotations, but actual weights should be calculated prior to installation.

Tile Weights (Laid Weight – Kg/m²)
MarleyRedland
Plain Clay80Cambrian Stone20
Feature70Saxon Slate50
Westwold100Richmond Slate60
Ludlow Plus50Stonewall Slate50
Anglia Plus50Delta Slate60
Double Roman50Norfolk Pantile50
Ludlow Major50Regent Tile50
Mendip50Grovebury Double Pantile50
Modern50Bridgewater50
Wessex6050 Double Roman50
Bold Roll50Renown Tile50
Supalite3049 Tile50
Monarch20Downland Plain50
 Plain Tile80
Rosemary Plain Clay80
Rosemary Cheslyn Clay90
 
EternitAnchor Roof Tiles
Rivendale20Bold Roll 8740
Eternit 200020Centurian30
Duracem20Senator40
Country20Vanguard 8330
Shire20Viscount40
Gower20Stone Slate50
 Anchorlite Slate30
Plain Tiles80
 
OtherDECRA
Natural Welsh Slate40Roofing System10
Metal Cladding System10Stratos10
General Tile Weights
TILE WEIGHTWeight Kg/m²
A.C. or Steel Sheet10
A.C. Slates20
Natural Slates30-40
Interlocking Concrete Tiles40-60
Plain Clay Tiles60-80
Concrete Slates90-100
Cotswold Stone100

Skew Fast over 125 mm requires a support tool for installation to prevent bending of the fixing.

There are two options of tools available:

  • Power Support Tool is installed into an SDS+ drill and enables installation of Skew Fast using the drill’s hammer action. The PST (below) is also able to install Skew Fast under 125 mm to sit flush with the counterbatten.                       
  • Hand Support Tool is a sleeve that fits over the Skew Fast to prevent bending when installing using a hammer. The HST (below) does not install the Skew Fast flush, but leaves around 50 mm out of the counterbatten to be finished by hand.
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Skew Fast calculator

This tool will calculate the number of Skew Fast warm roof fixings you will require on your project.
For pricing and availability, please contact Target's sales team.

Materials

mm
Above the rafter only. >150mm? Contact us.
mm
If <25mm or >50mm, contact us.
kg/m²
See the Tile Weight Guide.
mm
E.g. plyboard. May need pilot hole.

Construction

°
Use 90° for a wall.
m²
Include both elevations if needed.
Can halve number of fixings.

Rafters

mm
Measure between same points including width.

Location

Used for Wind Zone estimation.
See the Wind Zone Map if unsure.
Indicate how exposed the property is based on terrain.