roof ventilation
roof ventilation
complete roof ventilation
systems from Manthorpe
ventilation
requirements
One of the major problems experienced by
today’s energy conscious society is the build up
and subsequent effects of significant levels of
condensation in the roof space. This problem is
caused by the lack of adequate ventilation to the
roof void.
The British Standard BS 5250:2011 ‘Code of
practice for control of condensation in buildings’
is now cited as the industry standard regulation
throughout the UK and Ireland concerning roofing
ventilation, insulation and lining, detailing specific
requirements for various roof types.
Condensation is encouraged by the widespread use of insulating
materials, central heating and double glazing. Along with the
reduction in natural ventilation, the temperature differential between
the dwelling areas and the cold space is increased. The warm,
internal air carrying high levels of water vapour is naturally drawn,
by the process of convection, to the cold areas of the building
including the roof void.
Recommended ventilation amounts1:
In these areas, if there is insufficient ventilation, condensation
occurs causing rotting timbers, rusting and weakening of metal
fixings, felt damage and mould growth. Items stored in the loft
are often rendered useless and the general outcome involves
significant expenditure to rectify the problems.
To eliminate this unnecessary cost, Manthorpe manufactures a
range of quality roof ventilation products which are suitable for
new build and refurbishment situations.
Products available include:
• Continuous soffit and fascia vents
• Cross flow panels and lap vents
• Tile and slate vents
• Abutment and dry fix ridge ventilating systems
For a roof pitch of more than 15°,
10,000mm²/m is needed at the eaves
or low level. Pitches above 35° or
with span exceeding 10m, allow an
additional 5,000mm²/m at the ridge.
For roof pitches of 15° or less,
25,000mm²/m is required at the
eaves or low level to ensure a cross
flow of ventilation.
At dormer windows, fire barriers and
pitch changes etc, create separate
voids within the roof space. Ventilation
must be maintained to these areas at
high and low level as illustrated.
Mono-pitch roof details require a
5,000mm²/m ventilation gap at high
level, with a 10mm or 25mm gap at
low level depending on the roof pitch.
5*
*When the pitch
exceeds 35° or
span exceeds 10m
Roof Pitch Over 15°
10
10
25
25
Roof Pitch Below 15°
50mm
min gap
5
50mm
min gap
25
5
Flat Roof Dormer
25
*10mm or
25mm to suit
the pitch
10/25*
25
5
Mono Pitch Roof
If using a breathable roofing membrane with a non-air permeable
roof covering, look to allow 5,000mm²/m of ventilation at the ridge
with 25,000mm²/m into the batten void by use of counterbattens.
¹
Recommendations based on the guidance prodivided in BS 5250
and the NHBC Standards 7.2
eaves ventiltation solutions
G1280 Felt Support Tray
A
B
C
G1200N/G2500N Over Fascia Ventilator
Image shown is the G1290 Universal Roof Vent Pack
A G500 Roll Panel
B G1280 Felt Support Tray
C G1200N/G2500N Over Fascia Vents
The Manthorpe G1290/G1292 6 metre Ventilation Pack
provides a practical and cost effective solution for roof ventilation
requirements. The pack consists of a 6 metre run of Manthorpe
over fascia ventilator, roll panel and felt support tray, all the
products supplied in the pack are designed to comply with
Building Regulations and British Standards. Available for 10mm²
and 25mm² ventilation situations.
G500/G502 Continuous Roll Panels
The G1280 Felt Support Tray prevents roofing felt sagging at the
eaves, where water could collect and cause the felt to rot.
Designed with a smooth leading edge to fit on the top of the
fascia board, the slimline over fascia ventilator discreetly ensures
a positive passage of airflow into the roof space between the felt
and the fascia board making it ideal for new build and re-roofing
situations. The tray will fit any rafter centres and provides support
for the roofing felt, eliminating the problem of rotting felt by stopping
it sagging and retaining water at the eaves.
Over Fascia Ventilator
The G1200N gives 10mm² continuous airflow while the G2500N
provides 25mm² continuous airflow and is also suitable for use in
flat roof abutment situations.
The Continuous Roll Panel Eaves Ventilators G500/G502
provide a simple and economical solution to the problems
of eaves ventilation. Suitable for 400mm, 450mm and 600mm
raft centres, the panel has vertical strengthening ribs and is
suitable for new build situations. Its flexibility makes it suitable for
refurbishment where rafter centres are not consistent or unknown.
The G502 is adouble width version of the G500 to suit the high
levels of insulation used in modern building practice.
Both the G1200N and G2500N are produced in 1 meter
lengths to suit market demand. Products are robust enough
to be used with any/all Roof Tiles no matter what profile or
if fitted with plain tiles and/or slates. Designed with clear fixing
points both versions of the Manthorpe Over Fascia vent come
complete with a built in flyscreen. The G2500N has been
designed with a low profile enabling product to be easily fitted
and minimising the need to have to trim down fascia boards
prior to fixing.
G1281 Refurbishment Felt Support Tray
G800/G825 Continuous Soffit Ventilator
G1275 Eaves Comb Filler
G700 Circular Soffit Ventilator
The G1281 Refurbishment Felt Support Tray prevents felt
sagging at eaves level and subsequent pooling of water.
The G800/825 Continuous Soffit Ventilators are designed to
provide the solution to roof ventilation where a traditional soffit
board detail is specified.
The G1281 is simple to fit in new build or refurbishment
situations and eliminates the need to strip a large section of
the roof to replace old felt. This product is suitable for use with
many roof coverings, including breather membranes. The support
tray should be positioned on top of the fascia boards and secured
to the roof trusses, overlapped by minimum of 150mm. It should
be pushed under existing felt in refurbishment situations or in new
build situations felt should be dressed over the tray.
The G1275 Eaves Comb Filler is designed to prohibit entry of
birds and large insects below the eaves of profiled tiles.
The G1275 is designed with flexible fingers that adjust to fill
the gaps left when using profiled tiles eliminating the need
to make or buy expensive purpose made profiled fillers.
The product runs continuously along the top of the fascia
board above the felt and is nailed into position through the fixing
holes provided.
Manufactured in UPVC section, it is screwed onto the fascia and
securely supports the soffit board which is inserted into the self
retaining mouth. The airflow passage consists of evenly spaced
slots specifically sized to prohibit large insects gaining access, but
wide enough not to be blocked by debris.
A Continuous Sloping Soffit Ventilator product code G821 is
available for sloping eaves details. Low Pitch and Flat Roof Soffit
Ventilators product codes G826 and G827 are also available.
The G700 Circular Soffit Vent is designed to be fitted to the
soffit board prior to installation for new build situations.
The G700 can also be easily retro-fitted into existing soffit boards.
Standard fixing for this product is a simple push twist action into a
70mm hole drilled in the soffit board. The airflow passage consists
of evenly spaced slots specifically sized to prohibit large insects
gaining access but wide enough not to be blocked by debris,
paint or water droplets.
G400/G450/G600/G620 Cross Flow Eaves Panel
G435/G645 Refurbishment Eaves Panel Ventilator
G405/G455/G605/G625 Cross Flow Fly Screen Eaves Panel
G630 Felt Lap Ventilator
G405/G455 style shown left
G605/G625 style shown above
The Cross Flow Eaves Panel comprises rigid vacuum formed
trays designed to provide an air passage between the roof felt and
loft insulation to enable ventilation of the roof space.
The G435 and G645 Refurbishment Eaves Ventilator Panels are
designed to be used in refurbishment situations and are fitted from
within the roof space.
Sizes are available to encompass the majority of rafter centres.
Their flexibility allows them to fold to accommodate various roof
pitches. By tucking the insulation well into the fold of the ventilator
maximum airflow is achieved. Check product suitability with
insulation level required.
Manthorpe provides a range of rigid, flat pack, vacuum formed
panels designed for an easy fix for open eaves or cottage style
eaves. The panels include a 4mm fly screen.
The G400/G450/G600 range provides 10mm² of airflow through
each panel which are designed to suit 400mm, 450mm and
600mm rafter centres respectively. In addition to this range
Manthorpe produces a G625 product which provides 25mm²
airflow per panel for use with 600mm rafter centres.
The range of Cross Flow Fly Screen Eaves Panels product
codes G405/G455/G605/G625 have the addition of a series of
evenly punched holes and slots specifically designed to prohibit
the entrance of large insects but wide enough not to be blocked
by debris, paint or water droplets. These panels are ideally suited
to open eaves and cottage style eave details.
The G630 Felt Lap Vent is a refurbishment product designed to
increase the amount of ventilation into existing roof spaces.
The G630 is usually fitted retrospectively to properties with
additional loft insulation recently installed, however the Felt Lap
Vent will help to combat the problem of condensation build up
in any roof space with a lapped felt/membrane construction. The
product can be easily installed by one person in joist openings
from 400mm to 600mm wide to provide 3,000mm² of airflow per
unit. Please see fitting instructions and technical sheets regarding
the specific roof ventilation requirements.
tile and slate ventilators
GTV-MC Mini Castellated Vent
roofspace ventilation and mechanical extraction
solutions from Manthorpe
GTV-DR Double Roman Vent
GTV-NP Non-Profile Vent
GTV-CS Castellated Vent
GTV-DP Double Pantile Vent
The Manthorpe range of In-Line Tile Ventilators are designed to
provide roof space ventilation, or an outlet for ventilation ducting
through concrete and clay roof tile coverings. The range of six
profiles are universal in design and are compatible with the major
UK and Irish tile makes.
The in-line design gives a discreet, weather proof airflow path
through the roof covering with the recommended 4mm spaced
grill openings to prevent the entry of debris and large nesting
insects. The large format tile designs offer 10,000mm² of airflow
per unit, with the mini castellated offering 5,000mm² and the plain
tile providing 7,000mm².
Available in a range of four colours to suit most tile types, the vents
are quick and easy to install, with no need to cut the battens. A
sand faced version of the plain tile vent is also available.
GTV-PT Plain Tile Vent
GTV-PT-GRAN Sanded Plain Tile
GRSV30-25/45 Slate Vent
GRSV30-25R/45R Refurb Slate
The GRSV30-25 Slate Vent is designed to fit standard size
600mm x 300mm slates, but this can also be cut down to a smaller
size of 500mm x 250mm. The GRSV45 works with random slates
with a base size of 600mm x 450mm.
All sizes of slate vent allow 10,000mm² air flow per unit, providing
an unobtrusive, economical, high or low level roof ventilator.
Manufactured from UV stabilised durable polypropylene, the
vents have an integral insect grille and oval connection spigot
for mechanical extraction. Manthorpe’s slate vent has proved
outstanding in independent wind tunnel performance tests.
The fast fit refurb vents GRSV30-25R/45R, without the vent
spigot on the base, make retro-fitting into existing surrounding
slates easier. It is simply slid between natural or man made slates
already in position with no need to cut battens.
GTV-AD Flexi Pipe Adaptor
GRPA/GRPA2/GRPA3 Flexible Pipes
The vent tiles can also be used for
mechanical extraction, soil stack
or vent pipe termination.
The GRPA flexible pipe provides a quick and
easy connection between the slate vent and 4"
soil pipes or ventilation ducting systems.
For these details, the GTV-AD
Adaptor and the GRPA Flexible
Pipe range should be used.
The extra length GRPA2 makes connections
across a longer distance even easier, while the
GRPA3 allows a simple 4" to 3" pipe reduction.
abutment ventilation
ventilated ridge solutions
G1105 Abutment Flash Vent
GDRR Roll-Out Dry Fix Ridge System
GDRT SmartRidge - Dry Fix Vented Ridge Tile
Manthorpe designers have developed a revolutionary method for
venting abutment roof details which takes the fuss out of fixing.
The G1105 Flash Vent is a simple roll-out flexible sheet system
which provides a weather-tight solution to the need for a continuous
5,000mm²/m of airflow at roof abutment details.
The Manthorpe Roll-Out Dry Fix Ridge is a mechanically fitted
system which securely fixes the ridge tiles onto a roof. The GDRR
system provides 5,000mm²/m ventilation to the roof void through
the vent roll, the equivalent to a continuous 5mm gap.
Manthorpe’s Research and Development team has addressed the
need for a flexible and effective system by incorporating a series of
nodules into the design on both sides of the flexible vent roll. This
not only provides the required airflow but includes an integral fly
screen and maximises support of the lead.
The dry fix system means there is no need for mortar, making the
job of fixing the ridge quick, easy and clean, as well as making it
possible during frosts and other adverse weather conditions. The
system is compatible with most makes of concrete half-round and
angled ridge tiles and most slate, flat concrete and profiled tiles. A
single box provides all of the components required for a ridge run
approximately 6 metres in length (excluding the ridge tiles).
The G1105 Flash Vent is economical and easy to install as it is
formed from just one main component. It is supplied in a handy
box dispenser with no need for specialist fixing tools.
The SmartRidge Dry Ridge Tile System is a mechanically fixed
tile designed to replace clay and concrete ridge tiles with a plastic
moulded part.
Manthorpe’s G1105 has been independently wind tunnel tested
for weather tightness and can be used over profiled tiles, non
profiled tiles and slates without compromising its effectiveness.
The GDRT interlocking system makes the tiles very easy to fit and,
when completed, ensures an extremely secure finish.
A patented double comb prevents entry of wind-driven rain and
birds, while a 4mm fly screen provides 5,000mm2/m of continuous
ventilation into the roof space at ridge level. The textured finish,
available in Slate Grey, Dark Brown and Terracotta, is virtually
indistinguishable from traditional clay and concrete tiles.
Two widths can also be joined together to fit longer lengths of the
lap between the lead and the tiles, usually found on roofs with a
shallow pitch.
Product Specification Guide
Product Reference
Free
Size
Airflow mm2
Material
Integral
Colour
Insect Grille
Box
Qty
G500 Continuous Roll Panel
25,000
325mm wide
PET
Black
12LM
G502 Continuous Roll Panel
25,000
650mm wide
PET
Black
12LM
G600 Cross Flow Panel
10,000
450mm wide
PVC
Black
50
G620 Cross Flow Panel
25,000
450mm wide
PVC
Black
50
G625 Cross Flow Fly Screen Panel
25,000
450mm wide
PVC
Black
50
G450 Cross Flow Panel
10,000
350mm wide
PVC
Black
50
G400 Cross Flow Panel
10,000
350mm wide
PVC
Black
50
G605 Cross Flow Fly Screen Panel
10,000
450mm wide
PVC

Black
50
G455 Cross Flow Fly Screen Panel
10,000
450mm wide
PVC

Black
50
G405 Cross Flow Fly Screen Panel
10,000
450mm wide
PVC

Black
50
G435 Refurbishment Panel
25,000
250mm wide
PVC
Black
50
G645 Refurbishment Panel
25,000
250mm wide
PVC
Black
50
G1280 Felt Support Tray
-
625mm long
PVC
Black
50
G1281 Refurbishment Felt Support Tray
-
1.5m long
PVC
Black

10,000
6m long
G1292 Ventilation Pack
25,000
6m long
-
G1200N Over Fascia Ventilator
10,000
1m long
Polypropylene

Black
20
G2500N Over Fascia Ventilator
25,000
1m long
Polypropylene

Black
20
-
1m long
Polypropylene

Black
50
Polypropylene
White
50
G1275 Eaves Comb Filler
-
10
G1290 Ventilation Pack
6LM
6LM
G630 Felt Lap Vent
3,000
275 x 193.5 x 19mm
G800 Soffit Strip
10,000
2.44m long
UPVC

White/Brown/Black
10
G825 Soffit Strip
25,000
2.44m long
UPVC

White/Brown
10
G821 Sloping Soffit Strip
10,000
2.44m long
UPVC

White/Brown
10
G826 Soffit Strip
25,000
3.1m long
UPVC

Brown
10
G827 Soffit Strip
25,000
2.44m long
UPVC

White/Brown
10
G700 Circular Soffit
2,150
70mm dia.
Polypropylene

White/Brown/Black/Golden Oak
50
GTV-DR Double Roman Tile Vent
10,000
418 x 328mm
UPVC

Grey/Terracotta/Brown/Antique Red
4
GTV-NP Non-Profile Tile Vent
10,000
418 x 334mm
UPVC

Grey/Terracotta/Brown/Antique Red
4
GTV-CS Castellated Tile Vent
10,000
418 x 332mm
UPVC

Grey/Terracotta/Brown/Antique Red
4
GTV-DP Double Pantile Vent
10,000
418 x 332mm
UPVC

Grey/Terracotta/Brown/Antique Red
4
GTV-MC Mini Castellated Vent
5,000
390 x 230mm
UPVC

Grey/Terracotta/Brown/Antique Red
?
GTV-PT Plain Tile Vent
7,000
330 x 331mm
UPVC

Grey/Terracotta/Brown/Antique Red
6
GTV-PT-GRAN Granulated Plain Tile Vent
7,000
330 x 331mm
UPVC

Antique Brown/Old Red/Sand Red
6
GRSV30-25 Standard Slate Vent
10,000
600x300/500x250mm
Polypropylene

Black
10
GRSV30-25R Refurbishment Slate Vent
10,000
600x300/500x250mm
Polypropylene

Black
20
GRSV45 Random Slate Vent
10,000
600 x 450mm
Polypropylene

Black
5
GRSV45R Refurbishment Slate Vent
10,000
600 x 450mm
Polypropylene

Black
10
GTV-AD Flexi Pipe Adaptor
8,800
236 x 243mm
Polypropylene
Black
10
GRPA Flexible Pipe
8,000
455mm long
Polyethylene
Black
10
GRPA2 Flexible Pipe
8,000
800mm long
Polyethylene
Black
5
GRPA3 Reduction Adaptor
5,280
3/4
ABS
Black
10
G1105 Flash Vent
5,000
235 x 12 x 3,200mm
EVA

Black
3LM
GDRR Roll-Out Ridge System
5,000
6m long
-

Black/Dark Brown/Terracotta
6LM
GDRT Dry Ridge Tile System
5,000
472mm long each
UPVC/LDPE

Slate Grey/Terracotta/ Dark Brown
10
Manthorpe Building Products Ltd
Manthorpe House
Brittain Drive
Codnor Gate Business Park
Ripley, Derbyshire DE5 3ND
Tel: 01773 514 200
Email:bpsales@manthorpe.co.uk
www.manthorpe.co.uk
Associations
Manthorpe Building Products is a proud member of the NFRC.
References:
BRE
prEn 15601
BSI
BS 5250:2011
BSI
BS 5534:2003 + A1:2010
BSI
BS 491:2011
DOE
Building Regs. F2
NHBC
Good Practice Guide
NHBC
Standards 7.2
Manthorpe Quality
Manthorpe manufactures a range of ventilation and
building products at its headquarters in Derbyshire,
under a ISO9001 Quality Assurance Scheme.
All products are designed to comply with the
relevant current Building Standards when fitted in
accordance with the manufacturer’s instructions.
The company maintains a policy of continuous
development of its product range and reserves the
right to amend the specifications without notice.
Issue D
Published September 2014