Beam & Column Encasement
Fire Protection of the structural steel
framework.
Overview
Fire protection is required on structural steel beam and column
encasement for one reason only ... simply to keep the building
structure intact to allow everyone to escape to safety in the event
of a fire.
The effective fire protection of buildings is a growing concern
among designers as Building Regulations become more
stringent.
With the increasing use of structural steel in construction,
designers need options that provide a combination of fast
installation, cost effectiveness and to achieve the desired finish
every time.
Whatever the application Knauf Insulation has a range of board
products and systems to cater for any project.
Advantages
- are manufactured to factory tolerances. This allows the
specifier to be certain that the correct thickness of fire
protection is being applied, by simply checking the thickness of
materials supplied.
- can be installed prior to the building being sealed and made
watertight, in all temperature and humidity conditions. This is in
contrast to paint and sprays which are often restricted by normal
UK winter conditions, causing potential delay to site
programs.
- installation is fast, clean, dry and low dust causes minimal
impact on site, allowing other trades to work in close proximity or
immediately afterwards.
- are quick and easy to ensure that all relevant areas have been
protected.
- are totally compatible with drylining systems and allow easy
integration with a partitioning scheme.
- give beams and columns a superior appearance and impact
resistant (Fireboard) quality.
Knauf Insulation Products
- Knauf Fireboard is a gypsum based, fibre reinforced board
specially developed for high performance lining and frameless
encasement, offering up to two hours of fire protection. The
Fireboard product provides a smooth surface, ideal for the
application of decorative finishes.
- Rocksilk Firetech Slab is a high density rock mineral wool slab
providing up to four hours of fire protection. It is available
unfaced, tissue faced or with a bright Class ‘O’, reinforced
- aluminium foil. The Firetech product provides a cost effective
option for fire protection particularly in concealed areas.
- Rocksilk Firetech Dry Fix Slab is an ultra high density rock
mineral wool slab specially used for the noggin in the Rocksilk
Firetech Dry Fix Noggin System.
Summary
Knauf Insulation offers a range of certified fire protection
systems for structural steel beam and column encasement in either
concealed or exposed applications.
Detailed Design Considerations
Fire Protection
Any steel section which is an element of structure and is
deemed by any of the following regulations to require fire
resistance can be protected with a fire proofing system of dense
mineral wool slabs or fibre reinforced gypsum based boards.
- The Building Regulations 1991 Approved Document B3 Internal
Fire Spread/Structure, 2000 Edition
- The Building Standards Amendments (Scotland) Regulations 2001.
Technical Standards Part D6.
- The Building Regulations (Northern Ireland) 1994.
- Loss Prevention Council "Code of Practice for Construction of
Buildings".
- London Building Acts (Amendment) Act 1939, Section 20.
Steel sections can include universal beams, columns and joists
(plain and castellated), structural and rolled tees, angles,
channels and round, square or rectangular hollow sections.
Benefits
Both mineral wool and fibre reinforced gypsum offer a number
of advantages for the fire protection of structural steelwork that
make them ideal for fast track projects.
Achieving the Required Fire
Performance
The required thickness of the product depends upon the section
factor of the structural steel to be protected. The section factor
is the heated perimeter of the steelwork in metres, divided by the
cross sectional area of the steel in m2 (Hp/A or
A/V).
Calculating Hp
The table opposite displays the calculation formulae for Hp
for the major steelwork types and fire protection situations. All
dimensions are measured in metres.
Calculating A
A is the cross sectional area of the steel in m2.
This may be calculated from the dimensions of the steel section
itself, or from the formula:
Alternatively, use the "ready reckoner" tables below for common
universal beams and columns:
Ready reckoner for beams & columns
The tables below show the required Hp/A values for the
common dimensions of universal beams & columns
| Serial size mm (in) |
Mass/metre kg/m |
3-sided Hp/A |
4-sided Hp/A |
| 914 x 419 (36” x 16 1/2”) |
388 |
45 |
55 |
| 343 |
50 |
60 |
| 914 x 305 (36” x 12”) |
288 |
60 |
65 |
| 253 |
65 |
75 |
| 224 |
75 |
85 |
| 201 |
80 |
95 |
| 838 x 292 (33” x 11 1/2”) |
226 |
70 |
80 |
| 194 |
80 |
90 |
| 176 |
90 |
100 |
| 762 x 267 (30” x 10 1/2”) |
197 |
70 |
85 |
| 173 |
80 |
95 |
| 147 |
95 |
110 |
| 686 x 254 (27” x 10”) |
170 |
75 |
90 |
| 152 |
85 |
95 |
| 140 |
90 |
105 |
| 125 |
100 |
115 |
| 610 x 305 (24” x 12”) |
238 |
50 |
60 |
| 179 |
70 |
80 |
| 149 |
80 |
95 |
| 610 x 229 (24” x 9”) |
140 |
80 |
95 |
| 125 |
90 |
105 |
| 113 |
100 |
115 |
| 101 |
110 |
130 |
| 533 x 210 (21” x 8 1/2”) |
122 |
85 |
95 |
| 109 |
95 |
110 |
| 101 |
100 |
115 |
| 92 |
110 |
125 |
| 82 |
120 |
140 |
| 457 x 191 (18” x 7 1/2”) |
98 |
90 |
105 |
| 89 |
100 |
115 |
| 82 |
105 |
125 |
| 74 |
115 |
135 |
| 67 |
130 |
150 |
|
| Serial size mm (in) |
Mass/metre kg/m |
3-sided Hp/A |
4-sided Hp/A |
| 457 x 152 (18” x 6”) |
82 |
105 |
120 |
| 74 |
115 |
130 |
| 67 |
125 |
145 |
| 60 |
140 |
160 |
| 52 |
160 |
180 |
| 406 x 178 (16” x 7”) |
74 |
105 |
125 |
| 67 |
115 |
140 |
| 60 |
130 |
155 |
| 54 |
145 |
170 |
| 406 x 140 (16” x 5 1/2”) |
46 |
160 |
185 |
| 39 |
190 |
220 |
| 356 x 171 (14” x 6 3/4”) |
67 |
105 |
125 |
| 57 |
125 |
145 |
| 51 |
135 |
165 |
| 45 |
155 |
185 |
| 356 x 127 (14” x 5”) |
39 |
170 |
195 |
| 33 |
195 |
225 |
| 305 x 165 (12” x 6 1/2”) |
54 |
115 |
140 |
| 46 |
130 |
160 |
| 40 |
150 |
180 |
| 305 x 127 (12” x 5”) |
48 |
125 |
145 |
| 42 |
140 |
160 |
| 37 |
155 |
180 |
| 305 x 102 (12” x 4”) |
33 |
175 |
200 |
| 28 |
200 |
225 |
| 25 |
225 |
260 |
| 254 x 146 (10” x 5 3/4”) |
43 |
120 |
150 |
| 37 |
140 |
170 |
| 31 |
160 |
200 |
| 254 x 102 (10” x 4”) |
28 |
170 |
200 |
| 25 |
190 |
225 |
| 22 |
215 |
250 |
| 203 x 133 (8” x 5 1/4”) |
30 |
145 |
180 |
| 25 |
165 |
210 |
| 203 x 102 (8” x 4”) |
23 |
175 |
210 |
| 25 |
165 |
210 |
|
| Serial size mm (in) |
Mass/metre kg/m |
3-sided Hp/A |
4-sided Hp/A |
| 356 x 406 (14” x 16”) |
634 |
15 |
20 |
| 651 |
20 |
25 |
| 467 |
20 |
30 |
| 393 |
25 |
35 |
| 340 |
30 |
35 |
| 287 |
30 |
45 |
| 235 |
40 |
50 |
| 356 x 368 (14” x 14 1/2”) |
202 |
45 |
60 |
| 177 |
50 |
65 |
| 163 |
55 |
75 |
| 129 |
65 |
90 |
| 305 x 305 (12” x 12”) |
283 |
30 |
40 |
| 240 |
35 |
45 |
| 198 |
40 |
50 |
| 158 |
50 |
65 |
| 137 |
55 |
70 |
| 118 |
60 |
85 |
| 97 |
75 |
100 |
|
| Serial size mm (in) |
Mass/metre kg/m |
3-sided Hp/A |
4-sided Hp/A |
| 254 x 254 (10” x 10”) |
167 |
40 |
50 |
| 132 |
50 |
65 |
| 107 |
60 |
75 |
| 89 |
70 |
90 |
| 73 |
80 |
110 |
| 203 x 203 (8” x 8”) |
89 |
60 |
80 |
| 71 |
70 |
95 |
| 60 |
80 |
110 |
| 52 |
95 |
125 |
| 46 |
105 |
140 |
| 152 x 152 (6” x 6”) |
37 |
100 |
135 |
| 30 |
120 |
160 |
| 23 |
155 |
205 |
|
Performance Information
Establishing board thickness
To establish the board thickness required for steel column and beam
encasements, proceed as follows:
- Locate the appropriate size of beam or column on the table and
read off its Hp/A Factor depending on whether 3 or 4 sided
protection is required.
- Establish the period of fire resistance required.
- Refer to the adjoining table to determine the board thickness
required.
- For castellated sections, adopt the above procedure, then add
20% to the indicated thickness and specify the next highest
board.
Knauf Fireboard
Hp/A Table for Beams &
Columns
Thickness in mm for Knauf Fireboard for various periods of fire
resistance and section factors.
Rocksilk FireTech Slab
Hp/A Table for Columns
Thickness in mm for Rocksilk Firetech Slab for various periods of
fire resistance and section factors
Rocksilk FireTech Slab
Hp/A Table for Beams
Thickness in mm for Rocksilk Firetech Slab for various periods of
fire resistance and section factors
Specification
Knauf Fireboard
Knauf Fireboard, ...…mm thick, to be
used to provide fire protection to structural steelwork.
It is to be installed on beam*/column* as a complete*/3 sided*/2
sided* encasement (*specifier’s choice) to provide ......minutes
fire protection as detailed in the Installation section.
Please consult the
NBS based on Standard
Version K10 dated April 1997. It contains a set of proprietary
clauses, which are edited versions written by Knauf
Insulation.
Rocksilk Firetech Slab
Rocksilk Firetech Slab, ...…mm thick,
to be used to provide fire protection to structural
steelwork.
It is to be installed using the dry fix noggin system*/adhesive
noggin fixing system*/ combination fixing system*/welded pin fixing
system* (*specifier’s choice) as detailed in the Installation
section.