Metal Web
Floor System
Contents
Contents
Introduction and benefits
easi-joist®
definitions
easi-joist webs
4
5-6
Mechanical services
7
Loading and design
8
Floor stiffness
2
3
9
Internal non-loadbearing wall
10 - 11
Typical support details
12 - 13
Two ply girder and trimmer details
14
Edge closer details for timber frame and Internal bearing
15
Strongback installation and horizontal restraint strap details
16
Typical timber frame compartment floor and party wall with
service void detail
17
Layout, positioning and lifting
18
Flooring, fixing and fire resistance
19
I n t ro d u c t i o n a n d B e n e f i t s
Introduction
easi-joists are parallel chord trusses utilising stress graded timber
chords “on Flat” or “on Edge”.
These chords are plated together with a precision engineered and
manufactured structural component called the metal web, these
when combined form the easi-joist®.
The easi-joist® combines the lightness of timber with the structural
qualities of the metal web, together these two components offer an
opportunity for designing commercial, domestic and industrial floor
applications with spans equal to and exceeding traditional timber
joists and there equivalent timber alternative, but with better
damping and stiffness qualities.
easi-joist® is a precision designed and manufactured floor system,
that is designed to make floor joist manufacture faster, more cost
effective and easier to install.
Benefits
• Open web design
This allows for easier more
practical installation of services
including waste water pipes,
electrical cabling, heating pipes
and other services.
• Reduced site wastage
Precisely manufactured easi-joists
virtually eliminate all site alterations
this cuts out on waste and
pilfering.
• Light weight
The combination of smaller timber
sections with the light weight metal
web means that finished product is
lighter than timber and much
lighter than timber equivalents.
• Speed and ease of erection
As the timber is generally used “on
flat” the minimum 72mm width
allows for a speedy set out prior to
laying floor boards without the
need for temporary bracing.
• Top chord support
The easi-joist® is not limited in it’s
support capabilities options to
support on the top chord are
included.
• Long term stability
The reduced sections used in the
manufacture of the easi-joist®
combined with the metal web
means; that less loss of moisture
and shrinkage is seen meaning a
quieter and longer lasting floor
system.
• Comparative with timber
The easi-joist® system can be
manufactured to the minimum
depth required in the standard
codes of practice.
• Improved sound and
vibration
The metal web floor system allows
for the installation of a rigid
Strongback that reduces vibration
and improves the overall
performance of the floor.
3
easi-joist Definitions
Top chord
Top chord splice
Column
Metal Web
End column
Bottom chord
Column plate
Bottom chord splice
Strongback
Intermediate support
End bearing
4
e a s i - j o i s t We b s
36mm easi-joist
600mm
199mm
35mm
195mm
MS200
125mm
101mm
35mm
600mm
199mm
35mm
230mm
MS250
160mm
101mm
35mm
600mm
199mm
35mm
280mm
101mm
MS300
210mm
35mm
758mm
247mm
35mm
MS400
105mm
393mm
323mm
35mm
5
e a s i - j o i s t We b s
47mm easi-joist
600mm
199mm
47mm
219mm
MS200
125mm
101mm
47mm
600mm
199mm
47mm
254mm
MS250
160mm
101mm
47mm
600mm
199mm
47mm
304mm
101mm
MS300
210mm
47mm
758mm
247mm
47mm
105mm
417mm
323mm
47mm
6
MS400
Mechanical Services
easi-joists are designed to allow for
easy accommodation of electrical,
plumbing, waste water and other
services required within the floor joist
area with no cutting or notching
required.
D
A
H
W
The chords for easi-joist must NEVER
be cut, notched or drilled in any way
without written approval by a Wolf
Systems Ltd Engineer. Similarly the
metal webs must NEVER be drilled,
bent or removed for any reason.
Clearance for services
MS 200
MS 250
MS 300
MS 400
A (mm)
125
160
210
323
D (mm)
100
150
200
280
Clearance for rectangular services
MS 200
MS 250
MS 300
MS 400
H mm
W mm
W mm
W mm
W mm
50
300
300
330
500
100
100
200
250
410
150
50
70
170
330
200
N/A
N/A
70
250
250
N/A
N/A
N/A
170
300
N/A
N/A
N/A
70
7
Loading and Design
Dead loads
The weight of partition walls, floor
cover, ceilings, self weight of joist and
permanent services.
Live loads
(Imposed loads)
Everything not nailed down, loads
produced by the use and occupancy
of the of the floor, the load assumed
to be produced by the intended
occupancy or use including the
weight of movable partitions,
distributed, concentrated, impact
and inertia loads, but excluding
wind loads.
“It is essential that both distributed
live loads and point live load
requirements be considered
independently for various types of
floor loadings in accordance with the
specific British Standard associated
with floor loads – BS 6399: Part 1:
1996 incorporating amendment 1
(11/10/2002)”
Dead loads
Floor covering
Permanent services
Live loads
The easi-joist Software program will
allow the detailer/designer to specify
the live loads applicable to each
section of floor joist as these may
alter according to the use of the floor.
Any unusual loads that may be
required for the floor system i.e.
hoist loads, spa baths etc must be
checked and written confirmation
received from Wolf Systems Ltd
before proceeding.
Load warning
easi-joists are not designed to
support loadbearing walls. Any and
all roof and beam loads are to be
supported by external walls only,
Written confirmation from Wolf
Systems Ltd would be required in
advance should evidence of the
above load conditions be evident.
Further to this any additional loads
that may be imposed during
construction e.g. temporary support
of building materials that are likely to
have higher loads than those the
joists have been designed for must
be included in the design loads.
8
Unusual loads
Partition wall
F l o o r S t i ff n e s s
Factors affecting floor
stiffness
Factors affecting floor
damping
Strongback is sized, located and
fixed correctly to the easi-joists.
The dynamic action of any flooring
system whether timber, concrete or
steel is dependent on a number of
factors such as the eventual floor
plan, the applied loads and finally the
level of expectation of the occupants.
There are certain components of the
building structure which act together
and reduce vibration of the floor, this
is known as damping.
(Strongback grids are generally
provided at the centre of each
4000mm span)
One of the major contributors of the
damping effect (which will essentially
improve the easi-joist floor) is the
Strongback.
It is essential for both the structural
integrity and performance of the
easi-joist floor system that the
Other factors that that assist in the
damping effect are internal walls, this
is because in larger open areas floors
tend to have a more dynamic action.
Other contributors are floor and
ceiling covering and floor linings that
are correctly screwed to the joists to
reduce additional dynamic action
present in the floor.
Strongback posts can be inserted after
erecting joists should additional
Strongbacks be required
Strongback
Strongback grid designed
to automatically position the
Strongback correctly
9
I n t e r n a l N o n - l o a d b e a r i n g Wa l l s
Correct installation of
internal non-loadbearing
walls (parallel)
There are two accepted methods for
internal non loadbearing walls that
run parallel with the easi-joists
themselves.
In the case where fitted flooring
will be used after the internal wall is
constructed an additional easi-joist
will required below this wall to
support both the floor in addition
to the wall.
Walls that are parallel to the
easi-joist must have noggins at
600mm centres between joists to
support internal wall.
Method 1
Wall panel screw nailed onto
noggins with a minimum of
2 x 3.35 dia. galvanised nails
(length to suit)
47 x 97 noggins at
600mm c/c
Universal “Z” clip (or similar)
Method 2
Internal non-loadbearing wall
10mm gap required for
expansion and contraction of
floor material
Double easi-joist provided
under wall to support floor
material
10
I n t e r n a l N o n - l o a d b e a r i n g Wa l l s
Correct installation of
internal non-loadbearing
walls (perpendicular)
Again there are 2 accepted methods
with internal non-loadbearing walls,
placed perpendicular to the
easi-joists these do not require
additional support.
Method 1: Platform floor
Internal non-loadbearing wall
easi-joist
Method 2: Fitted floor
No additional support required for
fitted flooring with internal walls
perpendicular to the easi-joists
however a 10mm expansion gap is
required between the floor boards
and wall.
Internal non-loadbearing wall
10mm gap required
easi-joist
11
Ty p i c a l S u p p o r t D e t a i l s
Bottom chord bearings
Typical Support details for easi-joists
include and are mainly joists on
masonry hangers. The use of joist
hangers reduces the likelihood of
heat loss into the cavity and the
transmission of sound through the
separating walls.
Joist hangers must always
match the height of the joist
being used, this ensures
adequate lateral restraint,
failure to comply will mean
strapping each joist after
erection.
Joist /masonry hanger
Concrete beam
Joist to masonry hanger
Hanger depth must match
depth of joist
Concrete
Joist /masonry hanger
Internal
Joist to masonry hanger
Hanger depth must match
depth of joist
Block work/brickwork
Joist on timber frame
Stud wall
Flooring
Ceiling lining
Wall lining
12
Ty p i c a l S u p p o r t D e t a i l s
Top chord bearings
Joist on top chord
Extended top chord
on wallplate
Flooring
Ceiling
Joist on I beam,
hidden support
Hidden Top chord support allows for
continuous ceiling material.
Continuous top chord
Flooring
Ceiling
Joist on I beam
Extended top chord
Steel I beam
13
Tw o P l y G i rd e r a n d Tr i m m e r D e t a i l
Two ply girder
Two ply angles as specified by
designer
Extended hangers
Trimmer detail
Two ply angles as specified by
designer
Beam depth to suit, beam to
be slotted through both joists
Packing piece to maintain
ceiling line
14
Edge Closer Detail for Timber Frame
and Internal Bearing
Edge closer detail for
timber frame
50
mm
35mm edge closer
prefabricated faced with
plywood and including a
20mm lap at the top
Lateral restraint detail
47 x 72 top chord restraint
fixed to joists either between
joists or attached to bottom
chord web posts
Head binder to joists
Internal bearing
15
S t ro n g b a c k I n s t a l l a t i o n
and Horizontal Restraint Strap Details
Strongback sizes and
installation
easi-joist floor system and reducing
the deflection by load sharing.
Strongbacks are installed within the
easi-joist at right angles and their
purpose is to dampen the vibrations
by increasing the stiffness of the
Proper installation of the Strongback
and flooring material will ultimately
determine how well your easi-joist
flooring system will work.
m
0m
30
Fixing & splicing
Strongbacks must be fixed to
vertical webs in each easi-joist with
2 no 3.15 x 75mm Nails.
Strongbacks may be spliced where
required by using a 600mm section
equally over joint and nailed using
6 no 3.15 x 42mm nails on either
side of the join.
Splice positioning and nailing
positions
600mm Timber splice nailed by minimum
6 no nails either side
Splice joint
easi-joist
Nominal Size
Strongback size
TR26 Grade
Alternate Strongback
Lower Grade
MS200
72 X 35 TR26
97 X 35 C16
MS250
97 X 35 TR26
122 X 35 C16
MS300
122 X 35 TR26
142 X 35 C16
MS400
147 X35 TR26
172 X 35 C16
Horizontal restraint strap
Horizontal bracing straps are
required to be fixed to loadbearing
walls perpendicular to easi-joists.
This member must be continuous
over a minimum of three easi-joists.
97 x 35/47mm twice nailed to brace using
3.15 x 75mm long galvanised nails
Strap fixed with minimum of four fixings
of which at least one is to be over the
third joist
16
Ty p i c a l T i m b e r F r a m e C o m p a r t m e n t F l o o r
Service void
5mm (min) foamed
polyethylene resilient
flanking strip
resilient layer
easi-joist parallel to wall
easi-joist bearing on wall
20
0
ap mm
pro
x
Installation of
insulation
100m mineral wool insulation
quilt 23 kg/m2
Mineral wool cavity barrier
17
Layout, Positioning & Lifting
easi-joists typically placed
perpendicular to loadbearing walls.
Care should be taken to ensure that
the correct spacing between the
easi-joists as designed and indicated
on the layout is maintained throughout.
Never exceed design spacing.
Correct
The correct bearing should also be
maintained on every easi-joist as
specified.
Wrong
Lifting
easi-joists may be lifted in either
single units or packs but care should
be taken to eliminate twisting,
buckling, bending and dropping of
the Joists, Slings should always be
attached to the Timber Chord where
a panel point occurs.
18
45
F l o o r i n g , F i x i n g a n d F i re R e s i s t a n c e
Flooring and fixing
Explanation
There are many different types of
floor decking available the most
commonly used is pre-cut chipboard
in standard sizes, thickness may vary
from 18 to 22mm depending on the
spacing of the easi-joist®.
Any special instructions as indicated
by the manufacturers should be
noted.
Basic guidelines
Chipboard utilised in domestic
flooring should be as per BS
currently used for solid timber
equivalents.
Tongue and grooved boards should
be laid with the long edges running
perpendicular to the joists with joints
between the short edges occurring
on the centreline of the joist.
Square edged boards need to be
supported continuously along all
edges.
Joints along short edge boards
should be staggered and the length
of any board should generally not be
less than 2 x joist centres.
It is essential for a silent floor that
boards are supported with 50mm
of their edges at the perimeter of the
floor by either joist or perimeter noggin.
Fixings shall be of a minimum length
equal to 2.5 x board thickness
nails/screws should be positioned
8mm from board edge and 200mm
c/c along all supports and edges.
Chipboard is similar to other products
in that it expands and contracts
when exposed to high humidity,
therefore it is recommended that
a 10-12mm expansion gap left
between the boards and the face of
the brickwork. Further to this a 2mm
gap is recommended between
abutting boards.
Part E sound
Fire resistance
Tests are currently underway to
ascertain the minimum requirement to
ensure that the requirements Part E
are met fully. Wolf Systems suggest
that the details that currently apply
for solid joists which we assume to
be "worst case scenario", should
be utilised until such time as specific
robust details are approved and
agreed by local authorities.
All floors manufactured utilising
elements of timber rely on a
contribution from the ceiling for
overall fire resistance. Party floors
require a minimum of 2 No 12mm
Plasterboard to maintain the standard
fire regulations. Standard domestic
flooring requires minimum of
1 No 12mm Plasterboard.
The requirements for fire resistance
in domestic floors structures is
30 minutes and for party floors is
60 minutes.
Full scale fire testing will be initiated
to comply with European standards
for the easi-joist®, however for the
purpose of this initial manual it is
recommended that you utilise a
“Worst case scenario” Being a solid
timber joist and therefore strict
adherence to BS 5268: Part 4,
Section 2.1 is required.
Ceiling boards are to be positioned
such as their long edges run
perpendicular to the easi-joists.
The boards are fixed to the underside
of the joist using 3.2mm x 42mm
long approved fire resistant screws
positioned at 150mm centres.
Joints that do not occur at a joist
should be backed with a 75mm wide
strip of plasterboard of the same type
and thickness as the ceiling board
screw centres to be minimum
150mm centres.
All joints must be taped with an
approved fire resistant 50mm wide
fibre tape and filled with an
approved filler.
No apertures or service penetrations
should be present except where fitted
with an improved fire resistant fitting
(lights etc) or an appropriate fire
sealing system.
19
Wolf Systems Limited
Shilton Industrial Estate,
Shilton, Coventry CV7 9QL
T 08707 33 99 33
F 08707 33 99 55
E easi-joist@wolfsystem.co.uk
web site www.wolfsystem.co.uk