Authentic Wooden Box Sash Windows – Part or Full Replacement

In this case the southerly aspect had caused damage beyond reasonable repair so the box frames had to be stripped out to the masonry.

We’ve been around since the 80’s so you’re not leaving anything to chance when you engage with us. From TFL’s Victoria HQ to various country piles and from the RAF Club to Holland Park’s Debenham House and some pretty top notch K&C, Grosvenor Estate dwellings with Dulwich Estate properties and a wealth (too many to recall) of charming period housing stock in London and the home counties in between. Have a look at our front page gallery for more examples of our work.

…and so were replaced with high performance timber sash windows.



Each project we undertake, be it new sashes to existing  box sash window frames or complete renewal, we make all our windows in our south London joinery which not only means better fitting items but speedy problem solving. We adhere to traditional hand made joinery standards that ensure absolute authenticity.



We ensure our wooden sash windows are energy efficient meeting Part L Building Regulations when complete renewal is the order of the day. Over the years we’ve innovated and introduced various solutions that make producing authentic period sash windows that conform to today’s environmental demands not only possible but the norm.

Beaverwood School Chiselhurst during an extensive refurbishment to the box frames. The sashes were renewed into the original frame works.

…and after. Just in time for school!





Come and share our exhaustive knowledge gained over the last three decades.

The ‘railway cottages’ in Clapham


Sashpro back in the 90’s in Notting Hill

Call: 020 8819 3264 for a quick quote


 Click here for your free impartial buying advice guide and jargon buster for box sash windows

Double glazed sealed units produced in-house keep all our costs down

Since 2004 Building Regulations have had to be extended to include period properties. Even back as far as the early nineties Sashpro (not a Ltd company then) was coming up with ways to improve the weather performance of period windows. Sash windows have gone further with major changes in order to provide for the demanding environmental challenges that must be met.

As one of the first ‘modern’ firms to address the preservation of sash windows in general, Sashpro has helped to develop a number of innovations that make it possible for the period sash window

Sashpro durable weather-proofing

to remain in existence and be accountable ecologically. We developed a weather proofing system that not only addressed the traditional synonymous combination of the words draughty and sash window, now thankfully rendered apart but we did it completely invisibly. In other words it’s one of those clever devices you’ll never see, so sash windows remain unaffected aesthetically. All good so far but not good enough for building regs.

Sashpro glass stillage



Double glazing and traditional sash windows were never terms that sat happily together on the purists tongue however looking at the combination from the perspective that it was inevitable and thanks to a great Scottish inventor (whose needs might perhaps be considered greater up north!) Sashpro took a leap of faith and started to use the innovative Slim Sealed Unit. A low emissivity glass and the dense inert gas krypton, used instead of argon, along with ‘warm edge technology’ all allowed for the manufacture of super slim double glazing for sash windows, traditional timber casement windows and of course timber doors. We no produce our own sealed units which keeps costs considerably lower than most of our competitors. Great savings you can pass onto your customers to win the contract. We’ll provide help all along the way from product information, detailed specifications of works to final data sheets for your Building Control needs.

Sashpro slim sealed units

Sashpro slim sealed units





Allow these photos to explain

Here we can see that the sealed unit is virtually undetectable though it provides a U value of 1.5 meeting PartL Building Regs 2014 to current


Complicated sashes can be double glazed (and yes, that’s a lot of sawdust)

…and installed looking exactly like the original

Re-made to look exactly like the original below, double glazed and draught proofed

…and how the old one looked when we brought it back to the workshop





Click here to get in touch and find out more about our  double glazed sash windows in London, Surrey, Sussex and Kent.