Local Shutter InstallersOpenings · Survey
Thresholds and the bottom bar
Updated
The bottom bar wants a fair meeting with the sill. Sloped thresholds, clip-on ramps and bifold tracks leave gaps that waste the security and the draught claim.
What the wall will allow
See the bar on the actual sill during the survey, not on a showroom floor.
A worked pane
The worked opening for Thresholds and the bottom bar is 1.5 m wide by 2.1 m high, 3.15 square metres of glass. This figure puts 470 watts per square metre on the pane and uses a g-value of 0.63, about 933 watts into the room if the curtain is up. An opaque external shutter, taken as stopping 80 percent of that gain while it is fully down, leaves about 187 watts and keeps about 746 watts out. That is a noon figure for comparison. An internal blind does not get the same reduction. For Thresholds and the bottom bar, use the noon figure to compare two openings on the same house, then let a measured survey replace the figure.
An internal blind does not get that reduction, because the energy has already crossed the glass.
After dark
Winter figure for Thresholds and the bottom bar: glass at 1.2 W/m2K, 3.15 square metres, a 12 degree inside-outside gap and eight night hours. The bare pane is about 0.36 kWh a night on that crude sum. A closed shutter cutting about 18 percent of the flow leaves 0.30 kWh and saves about 0.07 kWh a night, only while it is down. Open it when you want winter sun.
Stop conditions
Stop Thresholds and the bottom bar if the only place for the box is a listed street front and nobody has written advice from the council. A photograph is not a manufacturing size.
Bath is only a setting for Thresholds and the bottom bar. The streets there are not the product.
How to use the figure
The 1.5 by 2.1 metre opening inside Thresholds and the bottom bar is there so a quote has something to disagree with. If the tape gives a different size, the tape wins.
The example drive is a belt, and the illustration is £2,132. A belt, a wired motor and a solar motor can share a curtain and still be different jobs. Compare those lines, not a single bold total.
What the survey still has to write down
For Thresholds and the bottom bar, ask where the box lands, what colour reference will be ordered, and how the curtain opens when the motor is dead. Those three answers move the job more than a rounded price.
Leave the lantern, the side light and the next elevation off the order unless they are drawn. Thresholds and the bottom bar covers one kind of opening. The house may have three.
When I would not order yet
Thresholds and the bottom bar should wait if the opening is an escape door with no way to raise a dead motor, or if the front is the elevation a conservation area was drawn to protect.
A photograph is not a manufacturing size. Two quotes for Thresholds and the bottom bar only compare when the slat, the box and the drive are the same kind of thing.
Questions worth asking the fitter
Is the price on this page a quote?
No. £2,132 illustrates Thresholds and the bottom bar for a 1.5 by 2.1 metre opening with a belt, at September 2026 rates. Your survey replaces it.
Does the shutter cover every pane?
It covers the opening it is built for. Here that example is 3.15 square metres. A roof lantern, a side light or the next elevation is another line.
What if planning is unclear?
Do not pay the factory for Thresholds and the bottom bar until a listed building, a conservation front, a flat or a shopfront has a written answer. Ordinary rear walls on houses are sometimes simpler.
What should two quotes share?
The same openings, the same slat type, and the same drive. Thresholds and the bottom bar uses a belt in the example so you can see how much the motor choice moves £2,132.