Sash Features

Window Construction

Mar 2, 2018 | Product Details, Uncategorized | 0 comments

Sash & Frame Construction

Our Sash and Frame Specifications

Our sashes are manufactured to a 54-64mm finish.

Standard sashes are usually 54mm thick allowing for a 4:14:4 double glazed unit. These sashes meet part L building regulations but are not as thermally insulative as our thicker sashes

Our Premium sashes are a minimum of 54mm thick but are 64mm thick when integrated blinds or triple glazing is specified. If engineered timber is used then a 60mm sash is our standard size which can incorporate a 4:16:4 IGU

Thicker sashes mean thicker double glazed units which yield a better U Value for thermal efficiciency. See here for more information regarding double / triple glazed units and U Values.

The stiles and top rail are finished at approx 60mm wide and the bottom rail is finished at 80mm wide. The deeper bottom rail allows us to use a stopped mortice and tenon guaranteeing the joint will not spread or drop and keeps the sash square with less chance of skewing over time.

Raw Materials

Starting out as rough sawn or engineered timber we plane and machine all our sash sections to ensure each element is square, straight and to size. All our timber comes from FSC certified forests. FSC helps take care of forests and the people and wildlife who call them home and is recognised by WWF as the “hallmark of responsible forest management”. The FSC ensures that forests are responsibly managed and stay alive for future generations.

Joinery Method

We use only traditional, time tested joinery methods to ensure our sashes stay perfect throughout their lifespan. Unlike many sash manufacturers we use mortice and tenon joints with D4 waterproof glues. Many manufacturers use D3 weatherproof glue and dowel joints which can fail in severe weather conditions.

Rebates In Or Out

Many manufacturers glaze internally for a security point of view. The beads cannot be removed from the outside so are deemed more secure. We disagree. All our sashes are manufactured to be beaded externally (Hodgson B6 system) and for good reason. Firstly it is almost impossible to remove a double glazed unit from the outside only. Our glazed units are bedded onto a butyl  flexi tape which adheres to the unit and seals to form a watertight barrier. Then the perimeter of the unit is sealed with glazing silicone which seals and adheres the unit in place. Thirdly, the beads are fitted using security glazing tape which adheres to the glass and can not be removed without totally destroying the glazing bead. The bead is also sat into the silicone perimeter seal and nailed every 200 mm. So the glazing beads are taped, siliconed and nailed, giving a neat and secure finish.

But why not glaze internally to be sure?

This is a simple question to answer.

If the perimeter seal does ever fail then water cannot ingress inwards. Water can only ever ingress up to our rebate and will find its way outwards. On internally beaded doors, once the perimeter seal has failed the only way water will go is inwards. Meaning leaks and unsightly water stains.

However. If you are still sure that internally beaded doors are your preferred choice, we are happy to bead internally.

Our sashes are supplied with the glass but require glazing after installation. This is due to weight and handling limitations.

Flush Casement Frame Specifications

Our flush casement frames are manufactured from 100x 63mm and 100 x 75mm timbers and are finished at approximately 90mm deep depending on the sash size chosen. Our standard design is square edge but we offer, stop chamfer, ovolo and lambs tongue as well as individual moulds to match existing joinery and we are used to conservation and listed requirements. The flush casement frame is designed to sit on a traditional stone sill. Sub sill grooves and window board grooves can be specified at the time of order. Window board grooves can be machined to take a standard internal window board with tongue or bespoke window board if required. Sub sills grooves can be machined at time of manufacture whilst the sub sill can be specified later if you are unsure of the projection you require. If you require either an outer or inner groove and sub sill and window boards please let us know via email when you order.

Our casement sashes are hinged on ball bearing stainless steel hinges with a traditional fastener and stay. If you require parliament hinges or a multipoint locking system or other means of locking then please let us know via email.

Bi Folding Window Frame Specifications

Our Bi folding window frames are approximately 144-154mm deep depending on the sash depth required. The frame jams and sill are finished at 45mm thick. We provide the sill in 2 versions to provide the drainage required for the bottom guide. The first version is a solid sill with a drainage channel housed in to take water from the bottom guide to the capillary drip of the projection sill. For this style of sill you will need to supply a projection measurement. If the window is sitting on a solid stone sill like a traditional flush casement window then a flush sill can be used. If you are unsure please give us a call and we can advise. On ordering please confirm the projection size via email along with any other requirements. The depth of the head section of the frame is 82mm on the inside and 62mm on the outside. We can alter these to suit your requirements.

Hardware Guide

We supply all the hardware you require for our window systems. Sashes will be prehung and fitted with standard fasteners and stays. Projecting hardware such as restrictor arms, trickle vents, and bulky fasteners will not be fitted due to the risk of damage during transport.


We are happy to work with architects and machine joinery to architectural specifications. If no architectural drawings are supplied then we will manufacture to our standard settings and designs. It is not our responsibity to check that the items ordered match your needs if no drawings are supplied, so we recommend the use of drawings.

It is the customers responsibility to ensure that the product ordered meets relevant regulations with regards to security, disabled access and thermal values. As not all joinery is required to meet certain regulations it is up to the customer to ensure, locking, glazing and access regulations are met by corresponding with the relevant persons, I.e. architects, building control etc. Please see full terms and conditions of sale for further details.



54 - 64mm Thick Sashes


Traditional Joinery Methods


FSC Certified Timber


10 Year Guarantee


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