DTT1Z Tension Tie & Holdown

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Product Details

DTT1Z

DTT1Z Illustration

DTT1Z-KT

DTT1Z-KTM

DTT1Z-KTM Opposing Stud Face Installation

DTT1Z-KT Opposing Stud Face Installation

DTT1Z-KT Adjacent Installation

DTT1Z-SDWH27800G-THD08140MG-SD9112

DTT1Z-KT Pack

Simpson Strong‑Tie offers a wide variety of holdown devices designed and tested to address many applications and load demands. The DTT1Z Tension Tie & Holdown is designed for lighter‑duty holdown applications on single or double studs. It can also be utilised in horizontal applications as a tension tie to provide balustrade or similar support. The DTT1Z is ideal for retrofit or new construction projects.

DTT1Z-KT (Timber) Bracewall Holdown Kit includes: (4) DTT1Z; (4) SDWH27800G; (24) SD#9 x 38mm
DTT1Z-KTM (Concrete) Bracewall Holdown Kit includes: (4) DTT1Z; (4)THD08140MG; (24) SD#9 x 38mm

Please check the Corrosion Information to see if it is suitable for your application.

Material

Carbon Steel 2mm thick

Finish

ZMAX^® Galvanised

Features & Benefits

The DTT1Z holdown bracket has engineered swages for extra strength and to minimise deflections
Designed for external and internal braced walls for concrete foundations and timber mid or sub-floors constructed in accordance with NZS 3604:2011, and exceeding the typically required 15kN holddown capacity
Can be installed anytime before plasterboard or wall lining
The load capacities are applicable for 20MPa concrete strengths
The M8 x 140mm Titen HD^® Heavy Duty Screw Anchor has serrated cutting teeth and patented thread design, which reduce installation torque, enable quick and easy installation into concrete
The SDWH27 structural timber screw requires no pre-drilling for installation into timber mid or sub-floor members
Installs easily with Strong-Drive SD9 Connector Screws

Installation

Installing the THD08140MG Screw Anchors into concrete slabs requires a minimum of 35mm edge distance and 78mm embedment, using a pair of DTT1 on opposing stud faces.
Installation into timber mid or sub-floors requires the SDWH27 installed centred in the 45mm timber members below, using a pair of DTT1Z either adjacent on the same stud face or on opposing stud faces
Follow the DTT1Z installation guide on the product flyer
Can be used as an alternative brace panel holdown in GIB EzyBrace^® Systems
Ref GIB^® Technical Support 18/03/2025

Applications

Holdown Applications including thermally insulated slabs
Resisting tension load applications
Deck-to-House Lateral Load Connection
Bracewall Holdown applications to concrete or timber substrates
Can be used as an alternative brace panel holdown in GIB EzyBrace® systems
Retrofit or new construction projects
Residential and commercial projects
Mid floor vertical connection applications
Engineered Wood Products (EWP)
Cross-Laminated Timber (CLT)

Approvals

BRANZ Appraisal 983 (2025) for external and internal braced walls for concrete foundations and timber mid or sub-floors constructed in accordance with NZS 3604:2011, and exceeding the typically required 15kN holddown capacity.
Can be used as an alternative brace panel holdown in GIB EzyBrace^® systems.

Model No. Table

Model No.	Dimensions (mm)					Fasteners		Minimum Timber Member Size (Depth x Breadth, mm)	Design Tension Capacity (kN) k1 = 1.14
	Strap Thickness	W	H	B	CL	Anchor Hole Dia (mm)	Post (Nails: No. - Length x Dia., Screws: No. - Dia. x Length, mm)
DTT1Z	2	38	181	37	19	10	6 – 40 x 3.75	90 x 38	5.0
							6 – SD#9 x 38		4.4
Design Capacity is the lesser of (1) the Characteristic Capacity multiplied by the NZ Strength Reduction Factor (φ), and applicable the k modification factors following NZS 3603 and (2) the Serviceability Capacity which is the load at 6.4mm joint slip, which includes fastener slip, anchor elongation and holdown deformation. Design Capacity is the minimum of test data and structural joint calculation. The Strength Reduction Factor (φ) is 0.80 for nails in lateral load and 0.70 for other fasteners. Duration of Load Factor (k1) is as shown. Reduce Duration of Load Factor where applicable. Capacities may not be increased. Timber species for joint design is seasoned Radiata Pine, which is New Zealand Joint Group J5 per NZS 3603 Table 4.1. The Designer must specify anchor bolt type, length and embedment. Anchor bolt nut should be finger tight plus 1/3 to 1/2 turn with a hand wrench. Care should be taken not to over-tighten the nut. Post or beam design by Designer. Posts may consist of multiple members provided they are connected independently of the holdown fasteners. Structural composite timber columns have sides that either show the wide face or the edges of the timber strands/ veneers, known as the narrow face. Simpson Strong-Tie stainless-steel connectors require stainless-steel fasteners. Values in the table reflect installation into the wide face. Holdowns and tension ties are for use in vertical or horizontal applications. Holdowns and tension ties may be installed raised up to 460mm above the top of the concrete with no load reduction, provided that additional elongation of the anchor rod is taked into account.

Technical Data - DTT1Z-KT (Timber) Bracewall Holdown Kit

Model No.	Dimensions (mm)					Fasteners		Minimum Timber Member Size (Depth x Breadth, mm)	Capacity
	Strap Thickness	W	H	B	CL	Anchor Hole Dia (mm)	Post (Nails: No. - Length x Dia., Screws: No. - Dia. x Length, mm)
DTT1Z (Holdown Bracket)	2	38	181	37	19	10	6 – SD#9 x 38	90 x 45	15kN/pair⁽²⁾
SDWH27800G (Anchor)	Size 7mm x 203mm⁽¹⁾; 3/8” Drive - Integrated Washer Head; SawTooth™ Type-17 Point; Hot Dipped Galvanised

(1) Minor diameter 7mm, major diameter 10mm.
(2) 15kN/pair installed at each end of Bracewall.

Technical Data - DTT1Z-KTM (Concrete) Bracewall Holdown Kit

Model No.	Dimensions (mm)					Fasteners		Minimum Timber Member Size (Depth x Breadth, mm)	Capacity
	Strap Thickness	W	H	B	CL	Anchor Hole Dia (mm)	Post (Nails: No. - Length x Dia., Screws: No. - Dia. x Length, mm)
DTT1Z (Holdown Bracket)	2	38	181	37	19	10	6 – SD#9 x 38	90 x 45	15kN/pair⁽¹⁾
THD08140MG (Anchor)	Size M8 x 140mm; 13mm Hex Head; Serrated Threads; Mechanically Galvanised

(1) 15kN/pair installed at each end of Bracewall.

Brochures & Catalogues

Brochures and Catalogues

Flyer - DTT1Z Tension Tie & Holdown

Technical Data & Docs

Technical Data Sheets

Technical Data Sheet - DTT1Z

Report

COLA_RR_25818

Report Links

BRANZ APPRAISAL No. 983 (2025)

Warranty

Alternative Products

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Simpson Strong‑Tie offers a wide variety of holdown devices designed and tested to address many applications and load demands. The DTT2 Tension Tie & Holdown is designed for lighter‑duty holdown applications on single or double studs.

HTT Tension Tie & Holdown

Simpson Strong‑Tie offers a wide variety of holdown devices designed and tested to address many applications and load demands.

HDU Heavy Duty Holdown

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Inspiration

DTT1Z-KT_Application_01.jpg

DTT1Z_Application_01.jpg

DTT1Z_Application_02.jpg

This is a Holdown! Introduction to Simpson Strong-Tie HDU, HTT and DTT ≠ Holdowns and Tension Ties

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DTT1Z Tension Tie & Holdown