Sash Restoration London
Head Office
Ripplevale Grove, 
Islington, London. 
N1 1HT
Tel:    0207-6093012
Mob: 07913372092
Sash Restoration St Albans
Hertfordshire Office
Blacksmiths Lane, 
St Albans. 
Tel:    0207-1646305
Mob: 07913372092 
Sash Restoration Reading
40 Wilton Road
RG30 2SS
Tel:    0207-1646305
Mob: 07913372092 

Slimline Double Glazing Windows for Conservation Areas In St Albans

Period timber windows are normally unable to accommodate double glazed units, and many planning authorities object to double glazing being installed in listed buildings and sensitive conservation areas in St Albans. Slimline double glazing is a viable alternative that is accepted by conservation officers in many cases. Sash Restoration St Albans supplies and installs Slimline double glazed units, designed to fit existing timber sash windows. By using a smaller, gas-filled gap between the glass panes, slimline double glazed units can achieve an energy rating on par with standard double glazing. This makes them perfect for heritage buildings and period homes across St Albans which are situated in conservation areas and need both the thermal benefits of energy efficiency and an authentic period appearance.

Slimline Glazing Window Features: 

  • Designed to replace single glazed windows in traditional box sash windows

  • Similar low U values to double glazing

  • In-keeping with traditional aesthetics

  • Ideal for listed buildings and properties in conservation areas


We work closely with a number of local authorities in London and St Albans and conservation officers to find the best solution for every property. If slimline double glazing is not approved, we can offer single glazing, secondary glazing and shutters.

Slimline double glazing windows we have fitted in St Albans:














Double Glazed Slimline Shutters 


We can also manufacture and install ultra slimline double glazed shutters that provide high levels of insulation, whilst remaining sympathetic to the building’s original design. Our glazed shutters do not interfere with the normal sashes during winter and can fold away discreetly in the summer for a practical alternative to slim double glazing.

Will it really look authentic? 

You will be hard pushed to tell the difference. At just 12mm thick, the units will be virtually undetectable. They look like single glazed windows, from inside and out. The units can be face puttied with traditional Linseed putty to give a truly traditional finish and can even be heat treated to give the glass a subtle warp, mimicking the hand blown look of yesteryear.

What about heat retention


The rate of heat loss through a given material is known as its U-value: the lower the U-value, the better it is at preventing it. The average single glazed window has a U-value of around 5.6. Slimlite double glazed units range between 2.2 and 1.5, up to almost three quarters less, keeping you warm and saving you money.

Can anyone have this done? 


Generally speaking yes but if you live in a listed building you will need to contact your local conservation officer to find out. Period frames are suitable and, where necessary, will be expertly restored by our experienced team, as part of the installation process. If not, they can be rebuilt to precisely match the originals.

For further information or if you have any questions regarding our slimline double glazing windows please contact us at: or call our head office on: 0207-6093012

Why restore your original timber sash & casement windows in St Albans?

Traditional double hung timber counterbalance sash windows have the best design and were built to last. They have stood the test of time. Made from traditional seasoned timber and quality hardwood sills the joinery on traditional sash windows was made when joiners had time to do their job properly and to last. Once restored you traditional windows will last for decades before repair is required unlike newer timber and aluminium window that are built of inferior materials and design, and only carry a one year guarantee. 

Is it a cost effective service?


Restoring your original timber sash or casement window with a full draught proofing installed is energy efficient and considerably cheaper than having a new complete box sash window supplied and fitted in your property.


Overview of our sash and casement restoration services:

Sash Cord Replacement

Top and bottom sash windows (4 cords) 

What you get: 


  • Remove all beading

  • Release top and bottom sashes

  • Remove weights

  • Sand sash friction points

  • Fit new sash cords

  • Oil pulley wheels

  • Re-install top and bottom sashes, existing parts and beading 

  • Remove rubbish

  • Vacuum room

Some beading or counterbalance weight's may need replacing (pricing for this may vary)

Draught Proofing System Fitted

We install a new brush pile draught seal into newly installed beading and existing meeting rails. This will reduce the noise and draught and lower your energy bills.

What you get:

  • Remove all beading and sashes

  • Fit brush pile draught system into new beading 

  • Check sashes for any loose joints

  • Fit brush pile draught system into meeting rail

  • Check glass and putty for damage

  • Replace any loose putty

  • Check pulley wheels are oiled and operating correctly

  • Check weights system is working correctly

  • Install new cotton sash cord for top and bottom windows (4 cords)

  • Re-install all new beading and sashes with existing fittings

  • Correct meeting rails to be flush if required

  • Set all beading correctly to allow for painting and smooth sliding windows

Counterbalance weight's may need replacing (pricing for this may vary)

Basic 3mm Clear Glass Replacement


Prices will vary depending on the size of your sash window. We can also supply 4mm clear glass for new sash windows

What you get:

  • Replace broken or cracked glass with new 3mm or 4mm glass

  • Timber glazing beads or oil putty glazing finish

  • We do not repair stained glass

Replace Sash Window Ironmongery


Good working sash ironmongery such as lockable sash locks and functional sash lifts are essential for a well-functioning window. The sash lock clamps the meeting rails tight for draught seal, and the sash lifts are designed to pull up the window correctly. Prices will vary depending on the style of the ironmongery

What you get:

  • Install new ironmongery in chrome, satin chrome or brass

  • We also can install child safe sash bolts, so your top or bottom window is secure when open at 100mm for ventilation in the day or at night to keep your property safe.

Timber Window Frame & Box Repairs

Replace rusted pulleys 

Install new window pockets 

What you get: 


Generally the timber frames and boxes of traditional sash windows are in good working condition but occasionally they will require timber repairs to the sill, new pulleys or window pockets. On the rare occasion they will need the architraves removed as the boxes are full of nails stopping the weights from functioning correctly. Flaking paint and minor holes are the job of the painter.

For further information or if you have any questions regarding our restoration service for sash and casement windows in St Albans please contact us at: or call our head office on: 0207-1646305