Gemini Traditional Sandfaced

Gemini Traditional Sandfaced

Colours and Finishes

Ideal for use in rural or established areas where blending with traditional older buildings is a must, the Gemini® Traditional Sandfaced roof tile is available in two colour blends.

This product is Kitemarked to BS EN 490 and a full range of mechanically fixed systems is available.

Mercia blend roof tiles
Gemini Traditional Sandfaced

Ideal for use in rural or established areas where blending with traditional older buildings is a must, the Gemini® Traditional Sandfaced roof tile is available in two colour blends.

This product is Kitemarked to BS EN 490 and a full range of mechanically fixed systems is available.

Please fill in the form below to request a printed version of this product's brochure, alternatively download an e-version on our Resources section.

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Can I install a conventional roof light with Forticrete Roof Tiles?

In most cases there is a suitable conventional roof light flashing kit which can be used with our products down to a roof pitch of 15 degrees. Forticrete would not recommend the installation of a conventional roof light below 15 degrees with profiled tiles.

Conventional roof lights when fitted below 15 degrees under certain weather conditions my seep water over flashing. Forticrete have a Low Pitch Roof Window solution, which when used with Forticrete Centurion tiles can be used at a pitch as low as 10 degrees. 

Do I need to ventilate my roof if I am using a breathable underlay?

Ventilation and control of ventilation is covered under BS 5250: (Code of Practice for control of Condensation in Buildings).

General information relating to traditional cold roof spaces

Breathable underlays work by transferring moisture laden air from inside the building into the batten cavity (the area between the top of the underlay and the underside of the tiles) where it is allowed to ventilate out between the gaps in the roof tiles or slates.

The gaps in between the tiles or slates will vary depending on the manufacturer and therefore additional ventilation may be required at the eaves or ridge line to assist in drawing the air in the batten cavity out of the roof.

Condensation forming on the back of the roof covering without adequate batten cavity ventilation may result 'Lime Staining' on the face of the tile.

In Forticrete's opinion additional ventilation should be provided at high level in the form of a ventilated ridge line. If the selected tile is flat additional ventilation should be used at the eaves.

Please consult with the tile, and underlay manufacturer for further advice.

General information relating to Warm Roof Spaces

Where the insulation is positioned between and on top of the rafter to the appropriate insulation level and is fully sealed is known as a warm roof.

In this instance no additional ventilation is required.


How is the Gemini tile clip fitted?

The Gemini tile clip is not mechanically fixed to the batten using a nail but clips the tail of one tile to the head of an underlying tile. To do this the clip is located on the underlock of the tile and locates under the back of the tile on the course below. The same method applies for the Minislate.

Gemini / Minislate Tile Clips

Slip Clip on to edge of tile

Slide Clip down the edge of tile

Slide Clip down until it reaches the top of the tile below

The Clip is then securely in place

How many clips are in a bag?

There are two types of clip available, either a tile clip or verge clip and these need to be ordered specifically by the tile being used.

  • Tile Clip - Pack of 100
  • Verge Clip - Pack of 50
How many tiles are on a pallet?

The table below outlines the quantity of Tiles or Fittings on a pallet, as well as, were relevant, the number of tiles in a pack/band.

Tile Pack Quantities

How many tiles are required for my roof?

Forticrete can provide a free take off service for roof areas in excess of 60m2 which will give an estimate of how many tiles and fittings you will need to order.

It is important that you fully specify what tiles, fittings and ventilation you require by filling in all parts of the estimate request form which is available as a word document or pdf format.

Side elevations and roof plans will be required with dimensions clearly marked on them.

All estimates are given as a guide that should be checked prior to ordering as any extra costs incurred due to over or under ordering will not be covered by Forticrete.

Please allow up to fifteen working days for return.

Site specific fixing specifications in line with BS5534 should be obtained prior to installation. You can request a fixing specification by visiting

How many tiles per m²

The number of tiles per m² will depend on the type used and in certain circumstances the pitch. The table below shows the number of tiles per m² for all Forticrete roof tiles.

How much ventilation do I need for my roof?

For duo pitch roofs over 15º and below 35º an eaves ventilation of 10,000mm/m² is required when the insulation is placed at ceiling level and 25,000mm/m² when the insulation is inclined to the rafters. For roof pitches over 35º or where the span across the gable end is greater than 10m, 5,000mm/m² high level ventilation is required.

For mono pitch roofs over 15º the eaves requirements are the same as for duo pitch roofs but high level ventilation is required at all pitches.

For all roof types below 15º the eaves ventilation requirement is 25,000mm/m².

How should I fix the tiles on my roof?

The exposure, location and roof design are all factors that will influence the tile fixing specification.

it is important that site and house type specific fixing specifications in line with BS5534 are obtained prior to installation.

Should you require a full fixing specification for your project, please visit

I have a roof pitch that is below the minimum recommended pitch for your tile. Is there anything that can be done?

Our roof tiles have been designed to perform down to their respective minimum pitches.

Below these pitches concrete tiles become purely decorative, and require a secondary waterproof barrier to be employed to carry any water down to the eaves and effectively discharge into the gutter.

There are several manufactures' that provide corrugated sheeting systems but these will always raise the overall height of the roof.

Otherwise a marine plywood deck can be installed with counter battens.

Apertures created in flat sub roof sheeting will have to be fully sealed around the up stands to allow water behind the opening to discharge around it.

Apertures cut into corrugated sub roof systems are not allowed as water in the corrugations above the junction will be trapped.

For further information please call the Technical Department on 01525 244900.

I have old tiles on my roof which have Anchor written on the back?

Anchor was taken over by Forticrete, though many of the tiles have since been withdrawn or have passed through product development. Generally the newer tiles do not course in with the older tiles.

One method that can be used is to find a porch or small dormer with the old tiles, use these for repairs, and then use the newer tiles for re-roofing the porch or dormer, as these are generally separate from the main roof.

I want to lay Centurion tiles on a roof pitch between 10° - 12.5° are there any restrictions?

The following restrictions apply for Centurion tiles at this pitch; the roof is not in an exposed location, it is a single storey lean-to with no hips or valleys with a rafter length less than 5m. All tiles are laid with a minimum100mm headlap. All tiles are tile clipped and verge clipped. Additionally ventilation must be in accordance with British Standards.

What distance does my first batten need to be up the roof?

The values below are based on the distance from the front of the fascia to the top of the batten with the exception of Hardrow and the Concrete Plain Tiles. The distances for these are based on the front of the fascia to the centre of the batten.

Double Lap Tiles such as Hardrow and Plain Tiles use an Undereaves Tile (often shortened to Eaves Tile), and the batten distance is given for these as well.


What height does my fascia need to be above the truss end?

The ventilated figures below assume that Forticrete's Eaves System is being used, which has a tray for supporting the underlay behind the Fascia. If an alternative form of ventilation is being used, the figure should be reduced by 6mm to allow for a 6mm plywood fillet to support the underlay.

What size of nails do I need for fixing my tiles?

The following table outlines the size of nail required to fix each of the Forticrete Roof Tiles:

What size of tiling batten should I use?

With truss or rafter spacing up to 450mm a 38x25mm batten should be used, spans greater than 450mm up to 600mm 50x25mm batten should be used. If concrete plain tiles are being used, 38x25mm batten can be used up to 600mm spacing.

When are ¾ tiles used?

The use of ¾ tile are used primarily for achieving the broken bond in the Gemini tile only and are used on a verge or a side abutment only. The ¾ tiles are not used on a hip or valley.

Which lead detail should I use at side abutments?

For flat profile interlocking tiles the recommended method of protecting a roof/wall junction is to install a continuous cover flashing and a secret gutter. With profiled interlocking tiles the recommendation is to provide a continuous cover flashing in lengths not greater than 1.5m. Further details can be sought for this from the Lead Sheet Association

Why do I have more RH ¾ tiles than LH ¾ tiles?

Wherever possible tiling should be carried out from right to left beginning with a full tile on the very first course then introduce a RH ¾ tile on the course above and on alternative courses thereafter, this will achieve the broken bond in the tiling pattern.

At the opposite verge or hip/valley a tile & half would be introduced and cut to suit.

The LH ¾ would only be used when tiling on a LH verge into a hip or valley.

The LH ¾ tile is minus the interlock and this is an easy way to distinguish the difference between the LH & RH ¾.

As with the RH ¾ tile this would also be used on alternative courses.